Method for manufacturing a fibrous material impregnated with thermoplastic polymer

ABSTRACT

An impregnated fibrous material comprising a fibrous material of continuous fibers and at least one thermoplastic polymer matrix, wherein at least one thermoplastic polymer is a non-reactive amorphous polymer whose glass transition temperature is such that Tp≥80° C., or a non-reactive semi-crystalline polymer whose melting temperature is Tf≥150° C., where Tg and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively, a fiber content by volume is constant in at least 70% of the volume of the impregnated fibrous material, the fiber content in said impregnated fibrous material being between 45 and 65% by volume on both sides of said fibrous material, a porosity rate in said impregnated fibrous material being less than 10%.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Application No.16/623,946, filed on Dec. 18, 2019, which is a U.S. national stage ofInternational Application No. PCT/EP2018/0066564, filed on Jun. 21,2018, which claims the benefit of French Application No. 1755705, filedon Jun. 22, 2017. The entire contents of each of U.S. application Ser.No. 16/623,946, International Application No. PCT/EP2018/0066564, andFrench Application No. 1755705 are hereby incorporated herein byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a method of manufacturing a fibrousmaterial impregnated with thermoplastic polymer.

More particularly, the invention relates to a method for manufacturingan impregnated fibrous material comprising a step for pre-impregnating afibrous material with a thermoplastic polymer for the preparation of animpregnated fibrous material, and a step for heating the thermoplasticmatrix in order to obtain ribbons of fibrous material impregnatedhomogeneously, in particular in the core, with reduced and controlledporosity, calibrated dimensions, usable directly to manufacturethree-dimensional composite parts.

In the present invention, “fibrous material” refers to an assembly ofreinforcing fibers. Before it is shaped, it assumes the form of rovings.After it is shaped, it assumes the form of strips (tapes), or plies.When the reinforcing fibers are continuous, their assembly constitutes aunidirectional reinforcement or a fabric or a nonwoven fabric (NCF).When the fibers are short, their assembly constitutes a felt or a fibermat.

Such impregnated fibrous materials are in particular suitable forproducing light composite materials for manufacturing mechanical partshaving a three-dimensional structure and having good mechanical andthermal properties. When the fibers are made from carbon or the resin isfilled with suitable additives, these fibrous materials are capable ofdischarging electrostatic charges. The use of flame-retardant resins orflame-retardant additives in resins that are not flame retardant allowsthe impregnated fibrous materials to withstand fires. They thereforehave properties compatible with the manufacture of parts in particularin the mechanical, aeronautics, naval, automotive, oil and gas, inparticular offshore, gas storage, energy, health and medical, sports andrecreation, and electronics fields.

Such impregnated fibrous materials are also called composite materials.They comprise the fibrous material made up of reinforcing fibers, andmatrix made up of the polymer impregnating the fibers. The first role ofthis matrix is to keep the reinforcing fibers in a compact shape and togive the desired shape to the final product. This matrix also ensuresthe charge transfer between the fibers, and therefore conditions themechanical strength of the composite. Such a matrix also serves toprotect the reinforcing fibers against abrasion and an aggressiveenvironment, to control the surface appearance and to disperse anycharges between the fibers. The role of this matrix is important for thelong-term holding of the composite material, in particular regardingfatigue and creep.

BACKGROUND ART

Good quality in three-dimensional composite parts manufactured fromimpregnated fibrous materials in particular involves mastery of themethod for impregnating reinforcing fibers with the thermoplasticpolymer.

In the present description, the term “strip” is used to refer to stripsof fibrous material having a width greater than or equal to 400 mm. Theterm “ribbon” is used to refer to ribbons with a calibrated widthsmaller than or equal to 400 mm.

The term “roving” is used to refer to the fibrous material.

To date, the manufacture of strips of fibrous material reinforced byimpregnation with thermoplastic polymer or thermosetting polymer wasdone using several methods that in particular depend on the nature ofthe polymer, the desired type of final composite material and its fieldof applications, some of these methods being constituted by animpregnation step followed by a step for hot rolling of the impregnatedfibrous material or a drying step optionally followed by a step formelting of the thermoplastic polymer.

Thus, wet impregnation technologies or those using a liquid precursor ora precursor with a very low viscosity, polymerizing in situ, are oftenused to impregnate the reinforcing fibers with thermosetting polymers,such as epoxy resins for example, as described in patent WO 2012/066241A2. These technologies are generally not directly applicable toimpregnation by thermoplastic polymers, since these rarely have liquidprecursors.

Impregnation methods by crosshead-die extrusion of a molten polymer aresuitable for the use of low viscosity thermoplastic polymers only.Thermoplastic polymers, in particular those with a high glass transitiontemperature, have a viscosity in the molten state that is too high toallow a satisfactory impregnation of the fibers and semi-finished orfinished products of good quality.

Application US 2014/0005331 A1 describes a method for preparing fibersimpregnated with a polymer resin, the obtained strip being asymmetrical,that is to say, it has one face that is rich in polymer and an oppositeface that is rich in fibers.

The method is done by molten route with a device only allowing majorityimpregnation on one of its faces.

Another known pre-impregnation method is the continuous passage of thefibers in an aqueous dispersion of polymer powder or aqueous dispersionof polymer particles or aqueous polymer emulsion or suspension.Reference may for example be made to document EP 0 324 680. In thismethod, a dispersion of micrometric powders is used (about 20 μm). Afterquenching in the aqueous solution, the fibers are impregnated by thepolymer powder. The method then involves a drying step consisting ofpassing the impregnated fibers in a first furnace in order to evaporatethe water absorbed during the quenching. A heat-treatment stepconsisting of passing the impregnated and dried fibers in a secondheating zone, at a high temperature, is next necessary to melt thepolymer so that it adheres, is distributed and covers the fibers.

The main drawback of this method is the homogeneity of the deposition,which is sometimes imperfect, coating done only on the surface.Furthermore, the particle size of the powders used is usually fine(typically 20 μm of D50 by volume), and this also increases the finalcost of the impregnated ribbon or ply.

Moreover, the drying step of this method causes a porosity in theimpregnated fibers by evaporation of the water.

The impregnated fibrous material must next be shaped in the form ofribbons, for example.

Companies market strips of fibrous materials obtained using a method forimpregnating unidirectional fibers by continuous passage of the fibersin a bath containing an organic solvent such as benzophenone, in whichthe thermoplastic polymer is dissolved. Reference may for example bemade to document U.S. Pat. No. 4,541,884 by Imperial ChemicalIndustries. The presence of the organic solvent in particular makes itpossible to adapt the viscosity of the polymer and ensure good coatingof the fibers. The fibers thus impregnated are next shaped.

They can for example be cut into strips of different widths, thenpositioned below a press, then heated to a temperature above the meltingtemperature of the polymer to ensure the cohesion of the material, andin particular the adherence of the polymer on the fibers. Thisimpregnation and shaping method makes it possible to produce parts witha structure having a high mechanical strength.

One of the drawbacks of this technique lies in the heating temperaturenecessary to obtain these materials. The melting temperature of thepolymers in particular depends on their chemical nature. It may berelatively high for polymers such as polyamide 6, or even very high forpolymers such as polyphenylene sulfide (PPS), HT polyamide, polyetherether ketone (PEEK) or polyether ketone ketone (PEKK), for example. Theheating temperature can therefore rise to temperatures above 250° C.,and even above 350° C., temperatures which are much higher than theboiling temperature and the flash point of the solvent, and which arerespectively 305° C. and 150° C. for benzophenone. In this case, thesolvent disappears quickly, causing a strong porosity within the fibersand therefore causing flaws to appear within the composite material. Themethod is therefore difficult to reproduce and incurs fire risks,endangering operators. Lastly, the use of organic solvents should beavoided for environmental reasons, as well as operator health and safetyreasons.

Document EP 0 406 067, filed in the joint names of Atochem and theFrench State, as well as document EP 0 201 367, describe a polymerpowder impregnation technique on fluidized bed. The fibers penetrate aclosed fluidization tank where, as concerns EP 0,406,067, they areoptionally separated from one another using ribbed rollers or cylinders,the fibers being electrostatically charged, by friction against theserollers or cylinders. This electrostatic charge allows the polymerpowder to stick on the surface of the fibers and thus to impregnatethem.

International application WO 2016/062896 describes a roving powdering byan electrostatic method with deliberate charge, by grounding of theroving and applying a potential difference between the tip of a spraygun or powdering nozzles and the roving.

Document WO 2008/135663 describes, in a third variant, the production ofa ribbon impregnated with fibers. In this document, the fiber ribbon isalready preformed before the impregnation step, in the form of a ribbonformed by fibers held together by means of support. The ribbon thuspreformed is charged beforehand with static electricity and submerged inan enclosure containing a fluidized bed of fine polymer particles insuspension in compressed air, so as to coat the ribbon with a polymercoating layer. Such a document does not make it possible to perform animpregnation of one or more fiber rovings simultaneously, or to performcontinuous shaping of the impregnated rovings in the form of ribbons.

Document EP 2 586 585 also describes the principle of impregnatingfibers by passing them in a fluidized bed of polymer particles. However,it does not describe the continuous shaping of one or more rovings thusimpregnated, in the form of one or more unidirectional parallel ribbons.

Application US 2002/1097397 describes a method for impregnating fibersby mixing polymer powders, said mixing being done directly in afluidized bed, without compounding.

International application WO 2015/121583 describes a method formanufacturing a fibrous material impregnated by impregnation of saidmaterial in a fluidized bed, then hot rolling said roving, allowingshaping of said roving(s) parallel to said material.

The hot rolling is done downstream from the impregnation device andmakes it possible to homogenize the distribution of the polymer and toimpregnate the fibers, but does not make it possible to obtain a ribbonimpregnated homogeneously. The porosity obtained is not quantified.

Document EP 0 335 186 describes the possibility of using a calendar orpress to compact a composite comprising impregnated metallic fibers,used to manufacture a molded body for shielding against electromagneticradiation. It does not describe impregnating one or more fiber rovingsand shaping them continuously, in the form of one or more unidirectionalparallel ribbons by heating after impregnation using a supporting partconducting heat and at least one heating system.

Document DE 1629830 describes a method for impregnating yarns by amultitude of strands reinforced by a fabric made from syntheticthermoplastic material comprising the following steps:

1) Passage of the yarns through a liquid phase of thermoplasticsynthetic material,

2) Passage through a scraper nozzle,

3) Passage through a channel heated to the temperature necessary forgelling or drying and plasticizing of the synthetic material driven bythe yarns,

4) Guiding through heated cylinders after leaving the heating channeland rolling of the rovings.

Document EP 2 725 055 describes a method for impregnation of a fibrousreinforcement by PEEK comprising the following steps:

1) Continuously supplying a fibrous reinforcement,

2) Combining the fibrous reinforcement and a PEEK oligomer to form acomposite,

3) Polymerizing the oligomer into poly PEEK,

4) Cooling and recovering the composite comprising the fibrousreinforcement and the poly PEEK.

Document EP 0 287 427 describes an impregnation method by molten routewith a spreading of the rovings with supporters.

A first spreading area with supporters makes it possible to spread thefibers before impregnating them by the molten route, then a secondheated supporting area is present.

Document JP 2013-132890 describes a method for producing plastic tapesreinforced by fibers, characterized in that the fibers pass through amachine for covering with thermoplastic resin, in particular acrosshead-die extruder, then impregnated fibers pass through a guide tocomprising an upper part and a lower part, the lower part being able tocomprise rollers and the guide being able to be heated.

WO 96/28258 describes a method not comprising spreading of the roving.

The fibers are introduced into a chamber for covering with powder inwhich the electrostatically charged particles of powder are deposited onthe fibers, then the rovings are introduced into a furnace in which theparticles are partially melted on the fibers and the impregnated fibersare next passed around a cooling roller.

Regarding the shaping of the impregnated fibers in the form ofcalibrated ribbons, suitable for manufacturing three-dimensionalcomposite parts by automatic deposition using a robot, this is generallydone in post-treatment.

Thus, document WO 92/20521 describes the possibility of impregnating afiber roving by passing it in a fluidized bed of thermoplastic powderparticles. The fibers thus covered with polymer particles are heated ina furnace, or a heating device, so that the polymer penetrates well andcovers the fibers. Post-treatment of the impregnated fibrousreinforcement obtained can consist of passing it in a set of calendarrollers making it possible to improve the impregnation by thestill-liquid matrix. Such a document does not make it possible toperform an impregnation of one or more fiber rovings and to performcontinuous shaping of the impregnated rovings in the form of one or moreunidirectional parallel ribbons.

The quality of the ribbons of impregnated fibrous material, andtherefore the quality of the final composite material, depends not onlyon the homogeneity of the impregnation of the fibers and therefore thecontrol and reproducibility of the porosity of the impregnated fibrousmaterial, but also the size and more particularly the width andthickness of the final ribbons. A regularity and control of thesetwo-dimensional parameters indeed makes it possible to improve themechanical strength of the obtained composite materials (from theribbons).

Currently, irrespective of the method used for the impregnation of thefibrous materials, the manufacture of thin ribbons, that is to say, witha width smaller than 400 mm, generally requires slitting (that is tosay, cutting) strips with a width greater than 400 mm, also calledplies. The ribbons thus sized are next taken back to be deposited by arobot using a head.

Furthermore, rolls of plies not exceeding a length in the order of 1 km,the ribbons obtained after cutting are generally not long enough tomanufacture certain large composite parts during deposition by robot.The ribbons must therefore be spliced in order to obtain a greaterlength, then creating excess thicknesses. These excess thicknesses leadto the appearance of heterogeneities that are detrimental to obtaininggood-quality composite materials constituting said composite parts.Additionally, these excess thicknesses require machine stoppages andrestarts of the robot, and therefore cause lost time and productivity.

The current techniques for impregnating fibrous materials and shapingsuch impregnated fibrous materials in the form of calibrated ribbonstherefore have several drawbacks. It is for example difficult to heat amolten mixture of thermoplastic polymers homogeneously in a die and atthe outlet of a die, to the core of the material, which alters thequality of the impregnation. Furthermore, the temperature differenceexisting between the fibers and molten mixture of polymers at theimpregnation die also alters the quality and homogeneity of theimpregnation. Furthermore, this impregnation mode by the molten routedoes not make it possible to obtain a high level of fibers or highproduction speeds due to the high viscosity of the thermoplastic resins,in particular when they have high glass transition temperatures, whichis necessary to obtain high-performance composite materials.

The use of organic solvents generally involves the appearance of flawsin the material as well as environmental, health and safety risks ingeneral.

The shaping, by post-treatment at high temperatures, of the impregnatedfibrous material in the form of strips, remains difficult because itdoes not always allow a homogeneous distribution of the polymer withinthe fibers, which causes the obtainment of a lower quality material,with a poorly controlled porosity.

The slitting of plies in order to obtain calibrated ribbons and thesplicing of these ribbons causes an additional manufacturing cost.Slitting further generates significant problems with dust that pollutesthe ribbons of impregnated fibrous materials used for robot depositionand can cause malfunctions of the robots and/or imperfections on thecomposites. This potentially incurs repair costs for the robots,production stoppages and the discarding of non-compliant products.Lastly, during the slitting step, a non-negligible quantity of fibers isdamaged, causing loss of property, and in particular a reduction in themechanical strength and conductivity, of the ribbons of impregnatedfibrous material.

Aside from the excess cost and the damage to the ribbons caused by theslitting, another drawback of slitting plies with a width greater than400 mm in particular is the maximum length of the ribbons obtained.Indeed, the length of these wide plies rarely exceeds 1000-1200 linearmeters, in particular due to the final weight of the obtained plies,which must be compatible with the slitting process. Yet to produce manycomposite parts by depositing calibrated ribbons, in particular forlarge parts, a coil of 1000 m is too short to avoid having to resupplythe robot during production of the part, here again incurring an excesscost. In order to increase the size of the slitted ribbons, it ispossible to splice several coils; this method consists of superimposingand hot welding two ribbons, incurring an excess thickness in the finalribbon, and therefore future defects during deposition with an excessthickness placed randomly in the final part.

Furthermore, the various methods described above do not allow ahomogeneous impregnation of the roving, which is detrimental to theapplications listed above.

The impregnation is not always done in the core, and while saiddocuments cited above indicate an impregnation to the core, the obtainedporosity may prove too substantial, in particular for the applicationslisted above.

SUMMARY

The invention aims to address at least one of the shortcomings of thebackground art. The invention in particular aims to propose a method ofmanufacturing an impregnated fibrous material, by a high-speedpre-impregnation technique followed by at least one step for heating thethermoplastic matrix for melting, or maintaining in the molten state,the thermoplastic polymer after pre-impregnation, using at least oneheat-conducting supporting part (E) and at least one heating system,with the exception of a heated calendar, and obtaining an impregnatedfibrous material having a homogeneous impregnation of the fibers, inparticular to the core, and controlled dimensions, with a reduced,controlled and reproducible porosity on which the performance of thefinal composite part depends.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a diagram of a heating system according to the inventionwith three rollers.

FIG. 2 describes a tank (10) comprising a fluidized bed (12) with asupporting part, the height (22) of which is adjustable. The edge of theinlet of the tank is equipped with a rotating roller 23 a over which theroving 21 a passes and the edge of the tank outlet is equipped with arotating roller 23 b over which the roving 21 b passes.

FIG. 3 describes an embodiment with a single compression roller, with atank (10) comprising a fluidized bed (12) in which a single cylindricalcompression roller (24) is present and showing the angle α₁.

The arrows at the fiber indicate the passage direction of the fiber.

FIG. 4 shows, but is not limited to, an embodiment with two compressionrollers R₁ and R₂, R₁ preceding R₂, with a tank (10) comprising afluidized bed (12) in which the two cylindrical compression rollers areat different heights relative to the bottom of the tank (R₂ at a heightH₂ above R₁ at a height H₁) are present and showing the angle α₁ and α₂.

The arrows at the fiber roving indicate the passage direction of thefiber.

FIG. 5 shows an exemplary embodiment with the tank (10) comprising afluidized bed (12) in which the two compression rollers R₁ and R₂ arecylindrical, at the same level relative to one another and side by sideand showing the angle α₁, and the angle α₂=0° and the roving passingbetween the 2 rollers.

FIG. 6 shows an exemplary embodiment with the tank (10) comprising afluidized bed (12) in which the two compression rollers R₁ and R₂ arecylindrical, at the same level relative to one another and side by sideand showing the angle α₁, and the angle α₂=90° and the roving passingbelow R₂.

FIG. 7 shows an exemplary embodiment with the tank (20) comprising afluidized bed (12) in which two compression rollers R₁ and R₂, R₁preceding R₂, at different levels are present and showing the angle α₁and α₂ and the roving passing below the roller R₂.

FIG. 8 shows an embodiment with a tank (10) comprising a fluidized bed(12) with two compression rollers R₁ and R₂, R₁ preceding R₂, and acompression roller R₃ and showing the angles α₁, α₂ and α₃.

FIG. 9 shows a photo taken with scanning electron microscopy of across-sectional view of a ¼″ Toray carbon fiber roving, 12K T700S M0Eimpregnated by a PA11/6T/10T D50=100 μm polyamide powder according tothe method described in WO 2015/121583 (after calendaring). The methodaccording to WO 2015/121583 shows a lack of homogeneity in severallocations of the impregnated roving diagrammed by the white arrows.

FIG. 10 shows the fluidization as a function of the air flow rate. Theair flow rate applied to the fluidized bed must be between the minimumfluidization flow rate (Umf) and the minimum bubbling flow rate (Umf).

FIG. 11 describes a tank (20) with a supporting part, the height (22) ofwhich is adjustable. The edge of the inlet of the tank is equipped witha rotating roller 23 a over which the roving 21 a passes and the edge ofthe tank outlet is equipped with a rotating roller 23 b over which theroving 21 b passes.

FIG. 12 shows an embodiment with a single compression roller, with atank (30) comprising a spray gun (31) for powder (32) in which a singlecylindrical compression roller (33) is present and showing the angleα″₁.

The arrows at the fiber indicate the passage direction of the fiber.

FIG. 13 shows, but is not limited to, an embodiment with two compressionrollers R″₁ and R″₂, R″₁ preceding R″₂, with a tank (30) each comprisinga spray gun (31) for spraying powder (32) and in which the twocylindrical compression rollers are at different heights relative to thebottom of the tank (R″₂ at a height H₂ above R″₁ at a height H₁) arepresent and showing the angle α″₁ and α″₂. The arrows at the fiberroving indicate the passage direction of the fiber.

FIG. 14 shows an exemplary embodiment with the tank (30) comprising aspray gun (31) for spraying powder (32) in which the two compressionrollers R″₁ and R″₂ are cylindrical, at the same level relative to oneanother and side by side and showing the angle α″₁, and the angle α″₂=0°and the roving passing between the 2 rollers.

FIG. 15 shows an exemplary embodiment with the tank (30) each comprisinga spray gun (31) for spraying powder (32) and in which the twocompression rollers R″₁ and R″₂ are cylindrical, at the same levelrelative to one another and side by side and showing the angle α″₁, andthe angle α″₂=90° and the roving passing below R″₂.

FIG. 16 shows an exemplary embodiment with a tank (30) each comprising aspray gun (31) for spraying powder (32) and in which two compressionrollers R″₁ and R″₂, R″₁ preceding R″₂, at different levels are presentand showing the angle α″₁ and α″₂ and the roving passing below theroller″₂.

FIG. 17 shows an embodiment with a tank (30) with two compressionrollers R″₁ and R″₂, R″₁ preceding R″₂, each comprising a spray gun (31)for spraying powder (32) and a compression roller R″₃ comprising a spraygun (31) for spraying powder (32) and showing the angles α″₁, α″₂ andα″₃.

FIG. 18 shows a photo taken with scanning electron microscopy of across-sectional view of a ¼″ Toray carbon fiber roving, 12K T700S 31Eimpregnated by a D50=51 μm PEKK powder according to the inventive methoddescribed in example 2. The diameter of a fiber represents 7 μm.

FIG. 19 shows a photo taken with scanning electron microscopy of across-sectional view of a ¼″ Toray carbon fiber roving, 12K T700S 31Eimpregnated by a D50=115 μm PA MPMDT/10T polyamide powder according tothe inventive method described in example 3. The diameter of a fiberrepresents 7 μm.

DETAILED DESCRIPTION

To that end, the invention relates to a method of manufacturing animpregnated fibrous material comprising a fibrous material made ofcontinuous fibers and at least one thermoplastic polymer matrix,characterized in that said impregnated fibrous matrix is produced as asingle unidirectional ribbon or a plurality of unidirectional parallelribbons and characterized in that said method comprises a step ofpre-impregnating said fibrous material while it is in the form of aroving or several parallel rovings with the thermoplastic material andat least one step of heating the thermoplastic matrix for melting, ormaintaining in the molten state, the thermoplastic polymer afterpre-impregnation,

the at least one heating step being carried out by means of at least oneheat-conducting supporting part (E) and at least one heating system,with the exception of a heated calendar,

said roving or rovings being in contact with all or part of the surfaceof said at least one supporting part (E) and partially or wholly passingover the surface of the at least one supporting part (E) at the level ofthe heating system.

Advantageously, said method excludes any electrostatic method withdeliberate charge.

Advantageously, said impregnated fibrous material is non-flexible.

The impregnation being done to the core in the inventive method, thismakes the impregnated fibrous material non-flexible, as opposed to theimpregnated fibrous materials of the art in which the impregnation ispartial, which leads to obtaining a flexible fibrous material.

Advantageously, said ribbon is impregnated with a high rate of fibers byvolume, between 45 to 65% by volume, preferably from 50 to 60% byvolume, in particular from 54 to 60%.

Advantageously, the rate of fibers by volume is constant in at least 70%of the volume of the strip or ribbon, in particular in at least 80% ofthe volume of the strip or ribbon, in particular in at least 90% of thevolume of the strip or ribbon, more particularly in at least 95% of thevolume of the strip or ribbon.

Advantageously, the distribution of the fibers is homogeneous in atleast 95% of the volume of the strip or ribbon.

The term “homogeneous” means that the impregnation is uniform and thatthere are no dry, that is to say, non-impregnated, fibers in at least95% of the volume of the strip or ribbon of impregnated fibrousmaterial.

The fiber rate by volume is measured locally on a representativeelementary volume (REV).

The term “constant” means that the fiber rate by volume is constant towithin any measurement uncertainty, which is plus or minus 1%.

The pre-impregnation step of the inventive method can be done usingtechniques well known by those skilled in the art, and in particularchosen from among those described above as long as the technology doesnot have any problems related to the use of organic solvents or forenvironmental and operator hygiene and safety reasons.

It can thus be done using a pre-impregnation technique by crosshead-dieextrusion of molten polymer, by continuous passage of the fibers in anaqueous dispersion of polymer powder or aqueous dispersion of polymerpowders or aqueous emulsion or suspension of polymer, by a dry polymerpowder, or by deposition of this powder, either in a fluidized bed, orby spraying of this powder through a nozzle or gun by dry route in atank.

The expression “supporting part (E)” refers to any system on which theroving can pass. The supporting part (E) can have any shape as long asthe roving can pass over it. It can be stationary or rotating.

The heating system is any system giving off heat or emitting radiationcapable of heating the supporting part (E). The supporting part (E) istherefore conductive or absorbs the radiation emitted by the heat.

The expression “heat-conducting supporting part (E)” means that thesupporting part (E) is made from a material capable of absorbing andconducting heat.

Said at least one supporting part (E) is located or comprised in theenvironment of the heating system, that is to say, it is not outside theheating system.

Said at least one supporting part (E) is therefore wholly inside theheating system. Advantageously, said heating system tops said at leastone supporting part (E). The heating system is at a sufficient heightfor the polymer present on the roving to be able to melt or to remain inthe molten state, depending on the technology used for thepre-impregnation, but without damaging said polymer.

Nevertheless, said heating system comprises either only said at leastone supporting part (E), or may also comprise a portion of the roving,outside said supporting system (E), said roving portion being locatedbefore and/or after said supporting system (E).

The height between the heating system and the supporters is between 1and 100 cm, preferably from 2 to 30 cm, and in particular from 2 to 10cm.

An illustration of a heating system and three supporters (E),corresponding to R′₁, R′₂ and R′₃, is shown in FIG. 1, but is in no waylimited thereto.

Of course, a second heating system can be present below the supporters,thus allowing uniform melting of said polymer on the two surfaces of theroving.

The heating system shown in FIG. 1 is a horizontal system. However, theheating system(s) can be positioned vertically also with verticalpassage of the roving through the supporters.

The Inventors have therefore surprisingly found that the heating step asdescribed above performed after the pre-impregnation step made itpossible, due to the partial or complete passage of said roving oversaid supporting part(s) (E), to obtain a contact surface with saidroving much larger than a calendar and thus to exert pressure on saidroving during a greater time than with a calendar, which results incausing a spreading of said roving at the level of the roller(s).

In parallel with this, the heating system also allows the heating of thesupporting part (E) and the roving pre-impregnated with thethermoplastic material, which can cause the melting of the thermoplasticpolymer on said roving even before its spreading and when the rovingcomes into contact with the first supporter (E or R′₁ in FIG. 1), itsspreading then allowing the homogeneous impregnation to the core thereofby the molten thermoplastic polymer with a very low porosity level thusleading to a high fiber rate by volume, in particular constant in atleast 70% of the volume of the strip or ribbon, in particular in atleast 80% of the volume of the strip or ribbon, in particular in atleast 90% of the volume of the strip or ribbon, more particularly in atleast 95% of the volume of the strip or ribbon.

The term “homogeneous” means that the impregnation is uniform and thatthere are no dry fibers in the impregnated fibrous material.

“Dry fiber” refers to a fiber devoid of polymer or not completelysurrounded by polymer.

As a result, this heating step makes it possible to perfect theimpregnation of the roving done beforehand during the pre-impregnationstep, and in particular to obtain a homogeneous impregnation to thecore.

It would not be beyond the scope of the invention if the supporting part(E) was not topped by a heating system, but directly connected to or incontact with a heating system such as a heat source or equipped with aresistance making it possible to heat said supporting part (E).

A heating calendar is precluded from the scope of the invention relativeto said heating system.

A heating calendar refers to a system of superimposed smooth or notchedcylinders between which the roving may circulate, said cylindersexerting a pressure on said roving to smooth and shape it.

There is therefore no shaping of said roving in said pre-impregnationstep and said heating step, in particular no precise control of thewidth and thickness of the ribbon in this stage of the method.

The expression “deliberately charged” means that a difference inpotential is applied between the fibrous material and the powder. Thecharge is in particular controlled and amplified. The grains of powderthen impregnate the fibrous material by attraction of the powder chargedopposite the fiber. It is possible to charge the powder electrically,negatively or positively, by different means (difference in potentialbetween two metallic electrodes, mechanical friction on metallic parts,etc.), and to charge the fiber inversely (positively or negatively).

The inventive method does not preclude the presence of electrostaticcharges that may appear by friction of the fibrous material on theelements of the implementation unit before or at the tank but that arein any case involuntary charges.

Polymer Matrix

Thermoplastic, or thermoplastic polymer, refers to a material that isgenerally solid at ambient temperature, which may be semi-crystalline oramorphous, and that softens during a temperature increase, in particularafter passage by its glass transition temperature (Tg) and flows at ahigher temperature when it is amorphous, or that may exhibit a sharptransition upon passing its so-called melting temperature (Tm) when itis semi-crystalline, and become solid again when the temperaturedecreases below its crystallization temperature (for semi-crystalline)and below its glass transition temperature (for an amorphous).

The Tg and Tm are determined by differential scanning calorimetry (DSC)according to standard 11357-2:2013 and 11357-3:2013, respectively.

Regarding the polymer making up the pre-impregnation matrix of thefibrous material, it is advantageously a thermoplastic polymer or amixture of thermoplastic polymers. This polymer or mixture ofthermoplastic polymers can be ground in powder form, so that it can beused in a device such as a tank, in particular in a fluidized bed oraqueous dispersion.

The device in tank form, in particular in a fluidized bed, can be openor closed.

Optionally, the thermoplastic polymer or blend of thermoplastic polymersfurther comprises carbon-based fillers, in particular carbon black orcarbon-based nanofillers, preferably selected from among carbonnanofillers, in particular graphenes and/or carbon nanotubes and/orcarbon nanofibrils or their blends. These fillers make it possible toconduct electricity and heat, and therefore to facilitate the melting ofthe polymer matrix when it is heated.

Optionally, said thermoplastic polymer comprises at least one additive,in particular chosen from among a catalyst, an antioxidant, a heatstabilizer, a UV stabilizer, a light stabilizer, a lubricant, a filler,a plasticizer, a flame retardant, a nucleating agent, a chain extenderand a dye, an electrical conductor, a heat conductor or a mixturethereof.

Advantageously, said additive is chosen from among a flame retardant, anelectrical conductor and a heat conductor.

According to another variant, the thermoplastic polymer or mixture ofthermoplastic polymers can further comprise liquid crystal polymers orcyclized polybutylene terephthalate, or mixtures containing the latter,such as the CBT100 resin marketed by the company CYCLICS CORPORATION.These compounds in particular make it possible to fluidify the polymermatrix in molten state, for better penetration to the core of thefibers. Depending on the nature of the polymer, or mixture ofthermoplastic polymers, used to make the pre-impregnation matrix, inparticular its melting temperature, one or the other of these compoundswill be chosen.

The thermoplastic polymers included in the composition of thepre-impregnation matrix of the fibrous material can be chosen fromamong:

-   -   the polymers and copolymers from the family of aliphatic,        cycloaliphatic or semi-aromatic polyamides (PA) (also called        polyphthalamides (PPA)),    -   polyureas, in particular aromatic polyureas,    -   polymers and copolymers from the family of acrylics such as        polyacrylates, and more particularly polymethyl methacrylate        (PMMA) or derivatives thereof,    -   polymers and copolymers from the family of        poly(aryletherketones) (PAEK) such as polyether ether ketone        (PEEK), or poly(aryletherketonesketones) (PAEKK) such as        poly(etherketoneketone) (PEKK) or derivatives thereof,    -   aromatic polyether-imides (PEI),    -   polyarylsulfides, in particular polyphenyl sulfides (PPS),    -   polyarylsulfides, in particular polyphenylene sulfones (PPSU),    -   polyolefins, in particular polypropylene (PP);    -   polylactic acid (PLA),    -   polyvinyl alcohol (PVA),    -   fluorinated polymers, in particular polyvinylidene fluoride        (PVDF), polytetrafluoroethylene (PTFE) or        polychlorotrifluoroethylene (PCTFE),

and mixtures thereof.

Advantageously, when said polymer is a mixture of two polymers P1 andP2, the proportion by weight of polymer P1 and P2 is between 1-99% and99-1%.

Advantageously, when said thermoplastic polymer is a mixture, and thepre-impregnation method uses a dry powder, this mixture assumes the formof a powder obtained by dry blend before introduction into thepre-impregnation tank or by dry blend done directly in the tank, or bygrinding a compound made beforehand in an extruder.

Advantageously, this mixture is made up of a powder obtained by dryblend, before introduction into the tank or directly in the tank, andthis mixture of two polymers P1 and P2 is a mixture of PEKK and PEI.

Advantageously, the PEKK/PEI mixture is from 90-10% to 60-40% by weight,in particular from 90-10% to 70-30% by weight.

The thermoplastic polymer can correspond to the final non-reactivepolymer that will impregnate the fibrous material or to a reactivepre-polymer, which will also impregnate the fibrous material, but whichmay react with itself or with another pre-polymer, depending on thechain end carried by said pre-polymer, after pre-impregnation, or with achain extender and in particular during heating at a heating calendar.

The expression “non-reactive polymer” means that the molecular weight isno longer likely to change significantly, i.e. that its number-averagemolecular weight (Mn) changes by less than 50% when it is used andtherefore corresponds to the final polyamide polymer of thethermoplastic matrix.

On the contrary, the expression “reactive polymer” means that themolecular weight of said reactive polymer will change during itsimplementation because of the reaction of reactive prepolymers togetherby condensation, substitution or with a chain extender by polyadditionand without the elimination of volatile by-products to lead to the final(non-reactive) polyamide polymer of the thermoplastic matrix.

According to a first possibility, said pre-polymer can comprise or beconstituted of at least one carrier reactive pre-polymer (polyamide) onthe same chain (that is to say, on the same pre-polymer), with twoterminal functions X′ and Y′ that are respectively co-reactive functionsrelative to one another by condensation, more specifically with X′ andY′ being amine and carboxy or carboxy and amine, respectively. Accordingto a second possibility, said pre-polymer can comprise or be constitutedof at least two polyamide pre-polymers that are reactive relative to oneanother and each respectively carry two identical terminal functions X′or Y′ (identical for same pre-polymer and different between the twopre-polymers), said function X′ of a pre-polymer being able to reactonly with said function Y′ of the other pre-polymer, in particular bycondensation, more specifically with X′ and Y′ being amine and carboxyor carboxy end amine, respectively.

According to a third possibility, said pre-polymer can comprise or beconstituted of at least one pre-polymer of said thermoplastic polyamidepolymer, carrying n terminal reactive functions X, chosen from among:—NH2, —CO2H and —OH, preferably NH2 and —CO2H with n being 1 to 3,preferably from 1 to 2, more preferably 1 or 2, more particularly 2 andat least one chain extender Y-A′-Y, with A′ being a hydrocarbonbisubstituent, bearing 2 identical terminal reactive functions Y,reactive by polyaddition with at least one function X of said prepolymera1), preferably having a molecular mass less than 500, more preferablyless than 400.

The number-average molecular weight Mn of said final polymer of thethermoplastic matrix is preferably in a range from 10000 to 40000,preferably from 12000 to 30000. These Mn values may correspond toinherent viscosities greater than or equal to 0.8, as determined inm-cresol according to standard ISO 307:2007 but by changing the solvent(use of m-cresol instead of sulfuric acid and the temperature being 20°C.).

Said reactive prepolymers according to the two options given above, havea number-average molecular weight Mn ranging from 500 to 10000,preferably from 1000 to 6000, in particular from 2500 to 6000.

The Mn are determined in particular by calculation from the rate of theterminal functions determined by potentiometric titration in solutionand the functionality of said pre-polymers. The masses Mn can also bedetermined by stearic exclusion chromatography or by NMR.

The nomenclature used to define the polyamides is described in ISOstandard 1874-1:2011 “Plastiques—Materiaux polyamides (PA) pour moulageand extrusion—Partie 1: Designation”, in particular on page 3 (Tables 1and 2) and is well known to the person skilled in the art.

The polyamide can be a homopolyamide or a co-polyamide or a mixturethereof.

Advantageously, the pre-polymers making up the matrix are chosen fromamong polyamides (PA), in particular chosen from among aliphaticpolyamides, cycloaliphatic polyamides, and semi-aromatic polyamides(polyphthalamides) optionally modified by urea units, and copolymersthereof, polymethyl methacrylate (PPMA) and copolymers thereof,polyether imides (PEI), polyphenylene sulfide (PPS), polyphenylenesulfone (PPSU), PVDF, polyether ketone ketone (PEKK), polyether eitherketone (PEEK), fluorinated polymers such as polyvinylidene fluoride(PVDF).

For the fluorinated polymers, it is possible to use a homopolymer ofvinylidene fluoride (VDF with formula CH₂═CF₂) or a copolymer of VDFcomprising, by weight, at least 50% by mass of VDF and at least oneother monomer copolymerizable with VDF. The VDF content must be greaterthan 80% by mass, or better still 90% by mass, in order to ensure goodmechanical and chemical resistance of the structural part, especiallywhen it is subject to thermal and chemical stresses. The co-monomer mustbe a fluorinated monomer, for example vinyl fluoride.

For structural parts having to withstand high temperatures, aside fromfluorinated polymers, according to the invention PAEK(polyaryletherketone) such as poly(ether ketones) PEK, poly(ether etherketone) PEEK, poly(ether ketone ketone) PEKK, Poly(ether ketone etherketone ketone) PEKEKK or PA with a high glass transition temperature Tg)are advantageously used.

Advantageously, said thermoplastic polymer is a polymer whose glasstransition temperature is such that Tg≥80° C., in particular≥100° C.,particularly≥120° C., in particular 140° C., or a semi-crystallinepolymer whose melting temperature Tm≥150° C.

Advantageously, said at least one thermoplastic prepolymer is selectedfrom among polyamides, PEKK, PEI and a mixture of PEKK and PEI.

Advantageously, said polyamide is selected from aliphatic polyamides,cycloaliphatic polyamides and semi-aromatic polyamides(polyphthalamides).

Advantageously, said aliphatic polyamide pre-polymer selected from:

-   -   polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12),        polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610        (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010),        polyamide 1012 (PA-1012), polyamide 11/1010 and polyamide        12/1010, or a mixture thereof or a copolyamide thereof, and the        block copolymers, in particular polyamide/polyether (PEBA), and        said semi-aromatic polyamide, is a semi-aromatic polyamide,        optionally modified with urea units, in particular a PA MXD6 and        a PA MXD10 or a semi-aromatic polyamide of formula X/YAr, as        described in EP1505099, in particular a semi-aromatic polyamide        of formula A/XT in which A is selected from a unit obtained from        an amino acid, a unit obtained from a lactam and a unit        corresponding to the formula (Ca diamine, Cb diacid), with “a”        representing the number of carbon atoms of the diamine and “b”        representing the number of carbon atoms of the diacid, “a” and        “b” each being between 4 and 36, advantageously between 9 and        18, the unit (Ca diamine) being selected from aliphatic        diamines, linear or branched, cycloaliphatic diamines and        alkylaromatic diamines and the unit (Cb diacid) being chosen        from aliphatic, linear or branched diacids, cycloaliphatic        diacids and aromatic diacids;

X.T denotes a unit obtained from the polycondensation of the Cx diamineand terephthalic acid, with x representing the number of carbon atoms ofthe Cx diamine, x being between 6 and 36, advantageously between 9 and18, in particular a polyamide with formula A/6T, A/9T, A/10T or A/11T, Abeing as defined above, in particular a polyamide PA 6/6T, a PA 66/6T, aPA 61/6T, a PA MPMDT/6T, a PA PA11/10T, a PA 11/6T/10T, a PA MXDT/10T, aPA MPMDT/10T, a PA BACT/10T, a PA BACT/6T, a PA BACT/10T/6T.

T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylene diamine and BACcorresponds to bis(aminomethyl)cyclohexane.

Fibrous Material:

The fibers making up said fibrous material are in particular mineral,organic or plant fibers. The mineral fibers include carbon fibers, glassfibers, basalt fibers, silica fibers, or silicon carbide fibers, forexample. The organic fibers include thermoplastic or thermosettingpolymer-based fibers, such as semi-aromatic polyamide fibers, aramidfibers or polyolefin fibers, for example. Preferably, they have a baseof an amorphous thermoplastic polymer and have a glass transitiontemperature Tg higher than the Tg of the polymer or thermoplasticpolymer mixture making up the pre-impregnation matrix when the latter isamorphous, or higher than the Tm of the polymer or thermoplastic polymermatrix making up the pre-impregnation matrix when the latter issemi-crystalline. Advantageously, they have a base of a semi-crystallinethermoplastic polymer and have a melting temperature Tm higher than theTg of the polymer or thermoplastic polymer mixture making up thepre-impregnation matrix when the latter is amorphous, or higher than theTm of the polymer or thermoplastic polymer matrix making up thepre-impregnation matrix when the latter is semi-crystalline. Thus, thereis no melting risk for the organic fibers making up the fibrous materialduring the impregnation by the thermoplastic matrix of the finalcomposite. The plant fibers include natural linen, hemp, lignin, bamboo,silk, in particular spider silk, sisal, and other cellulose fibers, inparticular viscose. These plant fibers can be used pure, treated orcoated with a coating layer, in order to facilitate the adherence andimpregnation of the thermoplastic polymer matrix.

The fibrous material can also be a fabric, a braid or woven with fibers.

It can also correspond to fibers with maintaining yarns.

These component fibers can be used alone or in mixtures. Thus, organicfibers can be mixed with the mineral fibers to be pre-impregnated withthermoplastic polymer and to form the pre-impregnated fibrous material.

The organic fiber rovings can have several grammages. They can furtherhave several geometries. The fibers can assume the form of cut fibers,which then make up the felts or mats able to take the form of strips,plies, or pieces, or the form of continuous fibers, which make up the 2Dfabrics, nonwovens (NCF), braids or rovings of unidirectional (UD) ornonwoven fibers. The component fibers of the fibrous material canfurther assume the form of a mixture of these reinforcing fibers withdifferent geometries. Preferably, the fibers are continuous.

Preferably, the fibrous material is made up of continuous carbon, glassor silicon carbide fibers or mixtures thereof, in particular carbonfibers. It is used in the form of a roving or several rovings.

In the impregnated materials, also called “ready to use”, the polymer ormixture of thermoplastic impregnation polymers is distributed uniformlyand homogeneously around the fibers. In this type of material, thethermoplastic impregnation polymer must be distributed as homogeneouslyas possible within the fibers in order to obtain minimal porosities,that is to say, minimal empty spaces between the fibers. Indeed, thepresence of porosities in this type of material can act as stressconcentration spots, during mechanical tensile stressing, for example,and which then form crack initiation points of the impregnated fibrousmaterial and mechanically compromise it. A homogeneous distribution ofthe polymer or mixture of polymers therefore improves the mechanicalstrength and homogeneity of the composite material formed from theseimpregnated fibrous materials.

Thus, in the case of so-called “ready to use” impregnated materials, thefiber rate in said pre-impregnated fibrous material is between 45 to 65%by volume, preferably from 50 to 60% by volume, in particular from 54 to60% by volume.

The impregnation rate can be measured by image analysis (using amicroscope or photo or digital camera device, for example), of across-section of the ribbon, by dividing the surface area of the ribbonimpregnated by the polymer by the total surface area of the product(impregnated surface plus surface of the porosities). In order to obtaina good quality image, it is preferable to coat the ribbon cut in itstransverse direction with a standard polishing resin and to polish witha standard protocol allowing the observation of the sample under amicroscope with at least 6× magnification.

Advantageously, the porosity level of said impregnated fibrous materialis less than 10%, in particular less than 5%, particularly less than 2%.

It must be noted that a nil porosity level is difficult to achieve andthat as a result, advantageously the porosity level is greater than 0%but less than the levels cited above.

The porosity level corresponds to the closed porosity level and can bedetermined either by electron microscopy, or as being the relativedeviation between the theoretical density and the experimental densityof said impregnated fibrous material as described in the examplessection of the present invention.

Pre-Impregnation Step:

The pre-impregnation step, as already indicated above, can be done usingtechniques well known by those skilled in the art and in particularchosen from those described above.

In one advantageous embodiment, the pre-impregnation step is done with asystem chosen from among a fluidized bed, a spray gun and the moltenroute, in particular at a high speed, particularly the impregnation isdone in a fluidized bed.

Advantageously, the pre-impregnation is done with a system chosen fromamong the fluidized bed, a spray gun and the molten route, in particularat a high speed, particularly the impregnation is done in a fluidizedbed and one or more supporting part(s) (E″) is (are) present upstreamfrom said system.

It should be noted that the supporting parts (E) and (E″) can beidentical or different whether in terms of the material or shape and itscharacteristics (diameter, length, width, height, etc. as a function ofthe shape).

Molten Route:

Advantageously, the pre-impregnation step is done by the molten route,particularly by pultrusion.

Pre-impregnation techniques by molten route are known by those skilledin the art and are described in the references above.

The pre-impregnation step is in particular done by crosshead-dieextrusion of the polymer matrix and passage of said roving(s) in thiscrosshead die, then passage in a heated nozzle, the crosshead dieoptionally being provided with stationary or rotary supporters on whichthe roving passes, thus causing a spreading of said roving allowing apre-impregnation of said roving.

The pre-impregnation can in particular be done as described in US2014/0005331A1, with the difference that the resin supply is done on twosides of said roving and there is no contact surface eliminating aportion of the resin on one of the two surfaces.

Advantageously, the pre-impregnation step is done by molten route at ahigh speed, that is to say, with a passage speed of said roving(s)greater than or equal to 5 m/min, in particular greater than 9 m/min.

One of the other advantages of the invention in combining apre-impregnation step and a heating step in the context of apre-impregnation by molten route is that the level of pre-impregnationfibers after the heating step is from 45% to 64% by volume, preferablyfrom 50 to 60% by volume, in particular from 54 to 60% by volume, saidfiber level not being able to be achieved by the conventional moltenroute techniques. This further makes it possible to work with highpassage speeds and thus to decrease the production costs.

Fluidized Bed:

Advantageously, the pre-impregnation step is carried out in a fluidizedbed.

An example unit for carrying out a manufacturing method without theheating step using at least one supporting part is described ininternational application WO 2015/121583.

This system describes the use of a tank comprising a fluidized bed forperforming the pre-impregnation step and can be used in the context ofthe invention.

Advantageously, the tank comprising the fluidized bed is provided withat least one supporting part (E′) (FIG. 2), which can be a compressionroller (FIG. 3)).

It should be noted that the supporting parts (E) and (E′) can beidentical or different whether in terms of the material or shape and itscharacteristics (diameter, length, width, height, etc.

as a function of the shape).

However, the supporting part (E′) is not heating or heated.

The step for pre-impregnation of the fibrous material is carried out bypassage of one or more rovings in a continuous pre-impregnation device,comprising a tank (10) provided with at least one supporting part (E′)and comprising a fluidized powder bed (12) of said polymer matrix.

The powder of said polymer matrix or polymer is suspended in a gas G(air, for example) introduced into the tank and circulating in the tank(10) through a hopper (11). The roving(s) are circulated in thisfluidized bed (12).

The tank can have any shape, in particular cylindrical orparallelepiped, particularly a rectangular parallelepiped or a cube,advantageously a rectangular parallelepiped.

The tank (10) can be an open or closed tank. Advantageously, it is open.

In the event the tank is closed, it is then equipped with a sealingsystem so that the powder of said polymer matrix cannot leave said tank.

This pre-impregnation step is therefore done by a dry route, that is tosay, the thermoplastic polymer matrix is in powder form, in particularsuspended in a gas, particularly air, but cannot be dispersed in asolvent or water.

Each roving to be pre-impregnated is unwound from a device with reelsunder the traction created by cylinders (not shown). Preferably, thereel device comprises a plurality of reels, each reel making it possibleto unwind a roving to be pre-impregnated. Thus, it is possible topre-impregnate several fiber rovings at once. Each reel is provided witha brake (not shown) so as to apply tension on each fiber roving. In thiscase, an alignment module makes it possible to position the fiberrovings parallel to one another. In this way, the fiber rovings cannotbe in contact with one another, which makes it possible to avoidmechanical damage to the fibers by friction relative to one another.

The fiber roving or the parallel fiber rovings then enter a tank (10),in particular comprising a fluidized bed (12), provided with asupporting part (E′) that is a compression roller (24) in the case ofFIG. 3. The fiber roving or the parallel fiber rovings next leave(s) thetank after pre-impregnation after optionally checking the residence timein the powder.

The expression “residence time in the powder” means the time duringwhich the roving is in contact with said powder in the fluidized bed.

The method according to the invention therefore comprises a firstspreading during the pre-impregnation step.

The use of at least one supporter (E′) in the pre-impregnation steptherefore allows an improved pre-impregnation relative to the methods ofthe background art.

“Supporting part (E′)” refers to any system on which the roving can passin the tank. The supporting part (E′) can have any shape as long as theroving can pass over it.

An example supporting part (E′), without restricting the inventionthereto, is described in detail in FIG. 2.

This pre-impregnation is done in order to allow the powder of saidpolymer matrix to penetrate the fiber roving and to adhere to the fibersenough to support the transport of the powdered roving outside the tank.

If the fibrous material, such as the glass or carbon fiber rovings, hasa sizing an optional de-sizing step can be carried out before thepassage of the fibrous material in the tank. The term “sizing” refers tothe surface treatments applied to the reinforcing fibers leaving thenozzle (textile sizing) and on the fabrics (plastic sizing).

“Textile” sizing applied on the fibers leaving the nozzle consists ofdepositing a bonding agent ensuring the cohesion of the fibers relativeto one another, decreasing abrasion and facilitating subsequent handling(weaving, draping, knitting) and preventing the formation ofelectrostatic charges.

“Plastic” sizing or “finish” applied on fabrics consists of depositing abonding agent, the roles of which are to ensure a physicochemical bondbetween the fibers and the resin and to protect the fiber from itsenvironment.

Advantageously, the pre-impregnation step is carried out in a fluidizedbed while checking that checking the residence time in the powder isfrom 0.01 s to 10 s, preferably from 0.1 to 5 s, and in particular from0.1 s to 3 s.

The residence time of the fibrous material in the powder is essential tothe pre-impregnation of the fibrous material.

Below 0.1 s, the pre-impregnation is not good.

Beyond 10 s, the polymer matrix level pre-impregnating the fibrousmaterial is too high and mechanical properties of the pre-impregnatedfibrous material will be poor.

Advantageously, the tank used in the inventive method comprises afluidized bed and said pre-impregnation step is carried out withsimultaneous spreading of said roving(s) between the inlet and theoutlet of the tank comprising said fluidized bed.

The expression “inlet of the tank” corresponds to the vertical tangentof the edge of the tank that comprises the fluidized bed.

The expression “outlet of the tank” corresponds to the vertical tangentof the other edge of the tank that comprises the fluidized bed.

Based on the geometry of the tank, the distance between the inlet andthe outlet thereof therefore corresponds to the diameter in the case ofa cylindrical tank, to the side in the case of a cubic tank or to thewidth or length in the case of a paralleliped-shaped tank. The spreadingconsists of singularizing each fiber as much as possible constitutingsaid roving from the other fibers that surround it in its most immediateenvironment. It corresponds to the transverse spreading of the roving.

In other words, the transverse spreading or the width of the rovingincreases between the inlet of the fluidized bed (or the tank comprisingthe fluidized bed) and the outlet of the fluidized bed (or the tankcomprising the fluidized bed) and thus allows an improvedpre-impregnation of the fibrous material.

The fluidized bed can be open or closed, in particular it is open.

Advantageously, the fluidized bed comprises at least one supporting part(E′), said roving(s) being in contact with part or all of the surface ofsaid at least one supporting part (E′).

FIG. 2 describes a tank (10) comprising a fluidized bed (12) with asupporting part (E′), the height (22) of which is adjustable.

The roving (21 a) corresponds to the roving before pre-impregnation thatis in contact with part or all of the surface of said at least onesupporting part (E′) and therefore passes at least partially or whollyover the surface of the supporting part (E′) (22), said system (22)being submerged in the fluidized bed where the pre-impregnation is done.Said roving leaves the tank (21 b) after checking the residence time inthe powder.

Said roving (21 a) may or may not be in contact with the edge of thetank (23 a), which can be a rotating or stationary roller, or aparallelepiped edge.

Advantageously, said roving (21 a) may or may not be in contact with theinlet edge of the tank (23 a).

Advantageously, the outlet edge of the tank (23 b) is a roller, inparticular cylindrical and rotating.

Said roving (21 b) may or may not be in contact with the outlet edge ofthe tank (23 b), which can be a roller, in particular cylindrical androtating or stationary, or a parallelepiped edge.

Advantageously, said roving (21 b) is in contact with the outlet edge ofthe tank (23 b).

Advantageously, the outlet edge of the tank (23 b) is a roller, inparticular cylindrical and rotating.

Advantageously, said roving (21 a) is in contact with the inlet edge ofthe tank (23 a) and the outlet edge of the tank (23 b) is a roller, inparticular cylindrical and rotating, and said roving (21 b) is incontact with the outlet edge of the tank (23 b), and the outlet edge ofthe tank (23 b) is a roller, in particular cylindrical and rotating.

Advantageously, said supporting part (E′) is perpendicular to thedirection of said roving(s). Said supporting part (E′) can be stationaryor rotating. Advantageously, said spreading of said roving(s) is done atleast at said at least one supporting part (E′).

The spreading of the roving is therefore done primarily at thesupporting part (E′), but can also be done at the edge(s) of the tank ifthere is contact between the roving and said edge.

In another embodiment, said at least one supporting part (E′) is acompression roller with a convex, concave or cylindrical shape,preferably cylindrical.

The convex shape is favorable to the spreading, while the concave shapeis unfavorable to the spreading, although it nevertheless occurs.

The expression “compression roller” means that the roving that passesbears partially or wholly on the surface of said compression roller,which causes the spreading of said roving.

Advantageously, said at least one compression roller is cylindrical andthe spreading percentage of said roving(s) between the inlet and theoutlet of the tank of said fluidized bed is between 1% and 1000%,preferably from 100% to 800%, preferably from 200% to 800%, preferablyfrom 400% to 800%.

The percentage of spreading is equal to the ratio of the final width ofthe roving to the initial width of the roving multiplied by 100.

The spreading depends on the fibrous material used. For example, thespreading of a material made from carbon fiber is much greater than thatof a linen fiber.

The spreading also depends on the number of fibers in the roving, theiraverage diameter and their cohesion due to the sizing.

The diameter of said at least one compression roller is from 3 mm to 500mm, preferably from 10 mm to 100 mm, in particular from 20 mm to 60 mm.

Below 3 mm, the deformation of the fiber caused by the compressionroller is too great.

Advantageously, the compression roller is cylindrical and not ribbed,and is in particular metallic.

When the supporting part (E′) is at least one compression roller,according to a first variant, a single compression roller is present inthe fluidized bed and said pre-impregnation is done at the angle α₁formed by said roving(s) between the inlet of said compression rollerand the vertical tangent at said compression roller.

The angle α₁ formed by said roving(s) between the inlet of saidcompression roller and the vertical tangent to said compression rollerallows the formation of an area in which the powder will concentrate,thus leading to a “corner effect” that, with the simultaneous spreadingof the roving by said compression roller, allows a pre-impregnation overa greater roving width and therefore an improved pre-impregnationcompared to the techniques of the improved background art.

Throughout the description, all of the provided angle values areexpressed in absolute value.

Advantageously, the angle α₁ is from 0 to 89°, preferably 5° to 85°,preferably from 5° to 45°, preferably from 5° to 30°. Nevertheless, anangle α₁ from 0 to 5° can cause risks of mechanical stress, which willlead to breaking of the fibers, and an angle α₁ from 85° to 89° does notcreate enough mechanical force to create the “corner effect”. A value ofthe angle α₁ equal to 0° therefore corresponds to a vertical fiber. Itis clear that the height of the cylindrical compression roller isadjustable, thus making it possible to position the fiber vertically. Itwould not be outside the scope of the invention if the wall of the tankwas pierced so as to be allow the exit of the roving. Advantageously,the inlet edge of the tank (23 a) is equipped with a roller, inparticular cylindrical and rotating, on which said roving(s) pass(es),thus leading to spreading prior to the pre-impregnation.

In one embodiment, the spreading is initiated at the inlet edge of thetank (23 a) and continues at said supporter(s) (E′) defined hereinabove.In another embodiment, one or more supporters (E″) are present upstreamfrom the tank comprising the fluidized bed at which the spreading isinitiated.

The supporters (E″) are as defined for (E) as regards the material, theshape and its characteristics (diameter, length, width, height, etc.based on the shape).

Advantageously, the supporters (E″) are cylindrical and non-ribbedrollers, and in particular metallic.

Advantageously, the diameter of said at least one compression roller isfrom 3 mm to 500 mm, preferably from 10 mm to 100 mm, in particular from20 mm to 60 mm.

Below 3 mm, the deformation of the fiber caused by the compressionroller is too great.

Advantageously, said at least one supporting part (E″) is made up of 1to 15 cylindrical compression rollers (R′″₁ to R′″₁₅), preferably 3 to15 compression rollers (R′″₃ to R′″₁₅), in particular 3 to 6 compressionrollers (R′″₃ to R′″₆).

Advantageously, said roving(s) form(s) an angle α′″₁ of 0.1 to 89°, inparticular of 5 to 75°, in particular of 10 to 45° with a firstcompression roller R′″₁ and the horizontal tangent to said compressionroller R′″₁, said roving(s) expanding in contact with said compressionroller R′″₁.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′″₁ of more than 89° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′″₁, this means that theroving has performed at least one complete revolution of said roller.

According to a second variant, said at least one supporting part (E) ismade up of two compression rollers, in particular cylindrical.

Advantageously, said roving(s) form(s) an angle α′″₁ of 0 to 180°, inparticular of 5 to 75°, in particular of 10 to 45° with a firstcompression roller R′″₁ and the horizontal tangent to said compressionroller R′″₁, said roving(s) expanding in contact with said compressionroller R′″₁.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′″₁ of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′″₁, this means that theroving has performed at least one complete revolution of said roller.

Advantageously, said roving(s) form an angle α′″₂ of 0 to 180°, inparticular of 5 to 75°, in particular of 10 to 45° with the secondcompression roller R′₂ and the horizontal tangent to said compressionroller R′₂, said roving(s) expanding in contact with said compressionroller.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₂ of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₂, this means that theroving has performed at least one complete revolution of said roller.

In general, the angle(s) α′″_(3-i) (i being from 3 to 15) formed by saidroving(s) with the rollers R′″₃₋₁ is(are) from 0 to 180°, in particularfrom 5 to 75°, particularly from 10 to 45°.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′″_(3-i), of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′_(3-i), this means thatthe roving has performed at least one complete revolution of saidroller.

In general, the height difference between each roller R′″_(i) andbetween the lowest roller and the highest roller is greater than orequal to 0.

Advantageously, the height difference between each of the rollersR′″_(i) is from 1 to 20 cm, preferably from 2 to 15 cm.

In general, the distance between each of the rollers R′_(i) is greaterthan 0, and in particular is from 1 to 50 cm, preferably from 2 to 30cm, in particular from 3 to 20 cm.

Advantageously, the spreading is initiated at the supporter(s) (E″)defined hereinabove and optionally continues at the inlet edge of thetank, then at said supporter(s) (E′) defined hereinabove.

The spreading is then maximal after passage at the compression roller(s)(E′).

Advantageously, the spreading percentage of said roving(s) between theinlet of the supporters (E″) and the outlet of the tank of saidfluidized bed is between 1% and 1000%, preferably from 100% to 800%,preferably from 200% to 800%, preferably from 400% to 800%.

FIG. 3 describes, but is not limited to, an embodiment with a singlecompression roller (24) or (R₁), with a tank (10) comprising a fluidizedbed (12) in which a single cylindrical compression roller is present andshowing the angle α₁.

The arrows at the fiber indicate the passage direction of the fiber.

Advantageously, the level of said powder in said fluidized bed is atleast located at mid-height of said compression roller.

It is clear that the “corner effect” caused by the angle α₁ favors theimpregnation on one face, but the spreading of said roving obtainedowing to the compression roller also makes it possible to havepre-impregnation on the other face of said roving. In other words, saidpre-impregnation is favored on one face of said roving(s) at the angleα₁ formed by said roving(s) between the inlet of said at least onecompression roller R₁ and the vertical tangent at said compressionroller R₁, but the spreading also makes it possible to impregnate theother face.

The angle α₁ is as defined above.

According to a second variant, when the supporting part (E′) is at leastone compression roller, then two compression rollers R₁ and R₂ are insaid fluidized bed and said pre-impregnation is done at the angle α₁formed by said roving(s) between the inlet of said compression roller R₁and the vertical tangent to said compression roller R₁ and/or at theangle α₂ formed by said roving(s) between the inlet of said compressionroller R₂ and the vertical tangent to said compression roller R₂, saidcompression roller R₁ preceding said compression roller R₂ and saidroving(s) being able to pass above (FIGS. 4 and 5) or below (FIGS. 6 and7) the compression roller R₂.

Advantageously, the two compression rollers have identical or differentshapes and are chosen from among a convex, concave or cylindrical shape.

Advantageously, the two compression rollers are identical andcylindrical, non-ribbed, and in particular metallic.

The diameter of the two compression rollers can also be identical ordifferent and is as defined above.

Advantageously, the diameter of the two compression rollers isidentical.

The two compression rollers R₁ and R₂ can be at the same level relativeto one another and relative to the bottom of the tank (FIGS. 5 and 6) oroffset relative to one another and relative to the bottom of the tank,the height of the compression roller R₁ being higher or lower than thatof the compression roller R₂ relative to the bottom of the tank (FIGS. 4and 7).

Advantageously, when the two rollers are at different heights and theroving passes above the roller R₂, α₂ is then from 0 to 90°.

Advantageously, said pre-impregnation is then done at the angle α₁formed by said roving(s) between the inlet of said compression roller R₁in the vertical tangent to said compression roller on a face of saidroving and the angle α₂ formed by said roving(s) between the inlet ofsaid compression roller R₂ and the vertical tangent to said compressionroller R₂ on the opposite face of said roving, which is obtained bypassing above the roller R₂.

Advantageously, said roving in this embodiment is subject to spreadingat each angle α₁ and a₂.

FIG. 5 describes, but is not limited to, an embodiment with twocompression rollers R₁ and R₂, R₁ preceding R₂, with a tank (10)comprising a fluidized bed (12) in which the two cylindrical compressionrollers, at the same level and side by side, are present and showing thecase where said roving(s) come out between said compression rollers R₁and R₂.

In this case, the angle αz is equal to 0 and said roving(s) pass abovethe roller R₂.

The arrows at the fiber indicate the passage direction of the fiber.

Alternatively, said roving(s) pass(es) at the inlet between saidcompression rollers R₁ and R₂ and come(s) out after having been incontact with part or all of the surface of said compression roller R₂.

Advantageously, said roving(s) is (are) in contact at the inlet withpart or all of the surface of said compression roller R₁ and come(s) outoutside the compression roller R₂ after having been in contact with partor all of the surface of said compression roller R₂, beneath the rollerR₂, the angle αz being formed by said roving(s) between the inlet ofsaid compression roller R₂ and the vertical tangent to said compressionroller R₂. In this case, the angle α=90°.

Said pre-impregnation is therefore done at the angle α₁ formed by saidroving(s) between the inlet of said compression roller R₁ in thevertical tangent to said compression roller on a face of said roving andthe angle α₂ formed by said roving(s) between the inlet of saidcompression roller R₂ and the vertical tangent to said compressionroller R₂ on the same face of said roving, but the spreading also makesit possible to impregnate the other face. Advantageously, said roving inthis embodiment is subject to spreading at each angle α₁ and α₂.

FIG. 6 shows an exemplary embodiment with two compression rollers R₁ andR₂ at the same level with respect to one another.

According to another embodiment of the second variant, when twocompression rollers are present, then the distance between the twocompression rollers R₁ and R₂ is from 0.15 mm to the length equivalentto the maximum dimension of the tank, preferably from 10 mm to 50 mm,and the height difference between the two compression rollers R₁ and R₂is from 0 to the height corresponding to the maximum height of the tanksubtracted from the diameters of the two compression rollers, preferablyfrom 0.15 mm to the height corresponding to the maximum height of thetank subtracted from the diameters of the two compression rollers, morepreferably a height difference between 10 mm and 300 mm, R₂ being theupper compression roller.

Throughout the description, the height difference between two rollersand the distance between two rollers (whether they are located upstreamfrom the tank, in the tank or at the heating system) is determinedrelative to the center of each roller.

Advantageously, when two compression rollers are present and at the samelevel relative to one another, the level of said powder in saidfluidized bed is at least located at mid-height of said two compressionrollers.

FIG. 7 describes, but is not limited to, an embodiment with twocompression rollers R₁ and R₂, R₁ preceding R₂, with a tank (10)comprising a fluidized bed (12) in which the two cylindrical compressionrollers at different levels are present and showing the angle α₁ and α₂.

The diameter of the compression rollers R₁ and R₂ is shown as identicalin FIGS. 4, 5, 6 and 7, but the diameter of each cylindrical compressionroller can be different, the diameter of the compression roller R₁ beingable to be larger or smaller than that of the compression roller R₂ inthe range as defined above.

Advantageously, the diameter of the two compression rollers isidentical.

It would not be going beyond the scope of the invention if thecompression roller R₁ was larger than the compression roller R₂.

According to a third variant, when two compression rollers are presentand at different levels, then at least one third compression roller R₃is also present and located between the compression rollers R₁ and R₂ inthe height direction (FIG. 8).

Advantageously, said roving(s) is (are) in contact at the inlet withpart or all of the surface of said compression roller R₁, then with partor all of the surface of said compression roller R₃, and come(s) outafter having been in contact with part or all of the surface of saidcompression roller R₂.

Advantageously, said pre-impregnation is done on a face of saidroving(s) at the angle α₁ formed by said roving(s) between the inlet ofsaid at least one compression roller R₁ and the vertical tangent to saidcompression roller R₁ as well as at the angle α₃ formed by saidroving(s) and the vertical tangent to said compression roller R₃ and onthe other face at the angle α₂ formed by said roving(s) and the verticaltangent to said compression roller R₂.

Advantageously, when two compression rollers are present at differentlevels and at least one third compression roller R₃ is also present,then the angle α₂ formed by said roving(s) between the inlet of said atleast one compression roller R₂ and the vertical tangent to saidcompression roller R₂ is from 180° to 45°, in particular from 120° to60°.

Advantageously, the angle α₃ is from 0° to 180°, advantageously from 45°to 135°.

FIG. 8 describes an embodiment, without being limited thereto, with atank (10) comprising a fluidized bed (12) with two compression rollersR₁ and R₂, R₁ preceding R₂, and a third compression roller R₃ andshowing the angles α₁, α₂ and α₃.

The diameter of the compression rollers R₁, R₂ and R₃ is shown asidentical in FIG. 8, but the diameter of each cylindrical compressionroller can be different, or two compression rollers can have the samediameter and the third can have a different, larger or smaller diameter,in the range as defined above.

Advantageously, the diameter of the three compression rollers isidentical.

Advantageously, in this third variant, a second control of the spreadingof said roving(s) is done at the compression roller R₃ and a thirdcontrol of the spreading is done at the compression roller R₃.

The residence time in this third variant is as defined above.

Advantageously, in this third variant, the level of said powder in saidfluidized bed is at least located at mid-height of said compressionroller R₂.

It would not be outside the scope of the invention if, in this thirdvariant, said roving(s) is(are) in contact at the inlet with part or allof the surface of said compression roller R₁, then with part or all ofthe surface of said compression roller R₂, and come(s) out after havingbeen in contact with part or all of the surface of said compressionroller R₃.

According to one advantageous embodiment, the present invention relatesto a method as defined above, characterized in that a singlethermoplastic polymer matrix is used and the thermoplastic polymerpowder is fluidizable.

The term “fluidizable” means that the air flow rate applied to thefluidized bed is between the minimum fluidization flow rate (Umf) andthe minimum bubbling flow rate (Umf) as shown in FIG. 10.

Below the minimum fluidization flow rate, there is no fluidization, thepolymer powder particles fall into the bed and are no longer insuspension, and the method according to the invention cannot operate.

Above the minimum bubbling flow rate, the powder particles fly away andthe composition of the fluidized bed can no longer be kept constant.

Advantageously, the volume diameter D90 of the particles ofthermoplastic polymer powder is from 30 to 500 μm, advantageously from80 to 300 μm.

Advantageously, the volume diameter D10 of the particles ofthermoplastic polymer powder is from 5 to 200 μm, advantageously from 15to 100 μm.

Advantageously, the volume diameter of the particles of thermoplasticpolymer powder is in the ratio D90/D10, or from 1.5 to 50,advantageously from 2 to 10.

Advantageously, the average volume diameter D50 of the particles ofthermoplastic polymer powder is from 10 to 300 μm, in particular from 30to 200 μm, more particularly from 45 to 200 μm.

The volume diameters of the particles of thermoplastic polymer powder(D10, D50 and D90) are defined according to standard ISO 9276:2014.

“D50” corresponds to the average diameter by volume, that is to say, thevalue of the particle size that divides the examined population ofparticles exactly in half.

“D90” corresponds to the value at 90% of the cumulative curve of theparticle size distribution by volume.

“D10” corresponds to the size of 10% of the volume of the particles.

According to another embodiment of the method according to theinvention, a creel is present before the tank comprising a fluidized bedto control the tension of the roving(s) at the inlet of the tankcomprising a fluidized bed.

Optionally, in the method according to the invention, one or moresupporters are present after the tank comprising the fluidized bed.

Optionally, a differential voltage is applied between the inlet and theoutlet of the tank used for the pre-impregnation step using a brake atthe outlet of said tank.

Step for Spraying by Gun:

The step for pre-impregnation of the fibrous material is done by passageof one or more roving(s) in a device for continuous pre-impregnation byspraying, comprising a tank (30), comprising one or more nozzle(s) orone or more gun(s) for spraying the polymer powder on the fibrousmaterial at the roller inlet.

The polymer powder or polymer is sprayed in the tank using nozzle(s) orgun(s) at the supporting part (E′) in particular of the compressionroller (at the inlet) on said fibrous material. The roving(s) arecirculated in this tank.

(E′) or the compression roller are as defined for the fluidized bed.

The tank can have any shape, in particular cylindrical orparallelepiped, particularly a rectangular parallelepiped or a cube,advantageously a rectangular parallelepiped.

The tank can be an open or closed tank. Advantageously, it is open.

In the event the tank is closed, it is then equipped with a sealingsystem so that the polymer powder cannot leave said tank.

This pre-impregnation step is therefore done by a dry route, that is tosay, the thermoplastic polymer matrix is in powder form, and sprayed inthe air, but cannot be dispersed in a solvent or water.

Each roving to be pre-impregnated is unwound from a device with reelsunder the traction created by cylinders (not shown). Preferably, thedevice comprises a plurality of reels, each reel making it possible tounwind a roving to be pre-impregnated. Thus, it is possible topre-impregnate several fiber rovings at once. Each reel is provided witha brake (not shown) so as to apply tension on each fiber roving. In thiscase, an alignment module makes it possible to position the fiberrovings parallel to one another. In this way, the fiber rovings cannotbe in contact with one another, which makes it possible to avoidmechanical damage to the fibers by friction relative to one another.

The fiber roving or the parallel fiber rovings then enter a tank (30),provided with a supporting part that is a compression roller (33) in thecase of FIG. 12. The fiber roving or the parallel fiber rovings nextcome(s) out of the tank after pre-impregnation after checking thespraying flow rate of said powder by said nozzle (or said nozzles) orsaid gun(s) on said fibrous material.

“Supporting part” refers to any system on which the roving can pass inthe tank. The supporting part can have any shape as long as the rovingcan pass above.

An example supporting part, without restricting the invention thereto,is described in detail in FIG. 11.

This pre-impregnation is done in order to allow the polymer powder topenetrate the fiber roving and to adhere to the fibers enough to supportthe transport of the powdered roving outside the tank.

The bath is provided with stationary or rotating supporters on which theroving passes, thus causing a spreading of said roving, allowing apre-impregnation of said roving.

The inventive method as indicated above is carried out by the dry route.

The inventive method does not preclude the presence of electrostaticcharges that may appear by friction of the fibrous material on theelements of the implementation unit before or at the tank but that arein any case involuntary charges.

Advantageously, the tank comprises at least one supporting part, saidroving(s) being in contact with part or all of the surface of said atleast one supporting part.

If the fibrous material, such as the glass fiber, has a sizing, anoptional de-sizing step can be carried out before the passage of thefibrous material in the tank. The term “sizing” refers to the surfacetreatments applied to the reinforcing fibers leaving the nozzle (textilesizing) and on the fabrics (plastic sizing).

“Textile” sizing applied on the fibers leaving the nozzle consists ofdepositing a bonding agent ensuring the cohesion of the fibers relativeto one another, decreasing abrasion and facilitating subsequent handling(weaving, draping, knitting) and preventing the formation ofelectrostatic charges.

“Plastic” sizing or “finish” applied on fabrics consists of depositing abonding agent, the roles of which are to ensure a physicochemical bondbetween the fibers and the resin and to protect the fiber from itsenvironment.

Advantageously, the spraying flow rate of the powder by the nozzle(s) orthe gun(s) is from 10 g/min to 400 g/min, in particular from 20 to 150g/min.

This flow rate is for each gun or nozzle and can be identical ordifferent for each gun or nozzle.

The spraying flow rate of the powder on fibrous material is essential tothe pre-impregnation of the fibrous material.

Below 10 g/min the air flow rate is not sufficient to convey the powder.Beyond 400 g/min, the state is turbulent.

Advantageously, said pre-impregnation step is carried out withsimultaneous spreading of said roving(s) between the inlet and theoutlet of said tank.

The expression “inlet of said tank” corresponds to the vertical tangentto the edge of the tank that comprises the roller(s) with nozzle(s) orgun(s).

The expression “outlet of said tank” corresponds to the vertical tangentto the other edge of the tank that comprises the roller(s) withnozzle(s) or gun(s).

Based on the geometry of the tank, the distance between the inlet andthe outlet thereof therefore corresponds to the diameter in the case ofa cylinder, to the side in the case of a cube, or to the width or lengthin the case of a paralleliped. The spreading consists of singularizingeach fiber as much as possible constituting said roving from the otherfibers that surround it in its most immediate environment. Itcorresponds to the transverse spreading of the roving.

In other words, the transverse spreading or the width of the rovingincreases between the inlet of the tank and the outlet of the tank andthus allows an improved pre-impregnation of the fibrous material.

The tank can be open or closed, in particular it is open.

Advantageously, the tank comprises at least one supporting part, saidroving(s) being in contact with part or all of the surface of said atleast one supporting part.

FIG. 11 describes a tank (20) comprising a supporting part, the height(22) of which is adjustable.

The roving (21 a) corresponds to the roving before pre-impregnation thatis in contact with part or all of the surface of said at least onesupporting part and therefore passes at least partially or wholly overthe surface of the supporting part (22), said system (22) beingsubmerged in the tank where the pre-impregnation is done. Said rovingleaves the tank (21 b) after checking the spraying flow rate of thepowder at the roller inlet.

Said roving (21 a) may or may not be in contact with the edge of thetank (23 a), which can be a rotating or stationary roller, or aparallelepiped edge.

Advantageously, said roving (21 a) is in contact with the inlet edge ofthe tank (23 a).

Advantageously, the outlet edge of the tank (23 b) is a roller, inparticular cylindrical and rotating.

Said roving (21 b) may or may not be in contact with the outlet edge ofthe tank (23 b), which can be a roller, in particular cylindrical androtating or stationary, or a parallelepiped edge.

Advantageously, said roving (21 b) is in contact with the outlet edge ofthe tank (23 b).

Advantageously, the outlet edge of the tank (23 b) is a roller, inparticular cylindrical and rotating.

Advantageously, said roving (21 a) is in contact with the inlet edge ofthe tank (23 a) and the outlet edge of the tank (23 b) is a roller, inparticular cylindrical and rotating, and said roving (21 b) is incontact with the outlet edge of the tank (23 b), and the inlet edge ofthe tank (23 b) is a roller, in particular cylindrical and rotating.

Advantageously, said roving (21 a) is in contact with the inlet edge ofthe tank (23 a) and a roller, in particular cylindrical and rotating,and said roving (21 b) does not touch the outlet edge of the tank (23b).

Advantageously, said supporting part is perpendicular to the directionof said roving(s).

Advantageously, said spreading of said roving(s) is done at least atsaid at least one supporting part.

The spreading of the roving is therefore done primarily at thesupporting part, but can also be done at the edge(s) of the tank ifthere is contact between the roving and said edge.

In another embodiment, said at least one supporting part is acompression roller with a convex, concave or cylindrical shape.

The convex shape is favorable to the spreading, while the concave shapeis unfavorable to the spreading, although it nevertheless occurs.

The expression “compression roller” means that the roving that passesbears partially or wholly on the surface of said compression roller,which causes the spreading of said roving.

Advantageously, said at least one compression roller is cylindrical andthe spreading percentage of said roving(s) between the inlet and theoutlet of said tank is between 1% and 1000%, preferably from 100% to800%, preferably from 200% to 800%, preferably from 400% to 800%.

The spreading depends on the fibrous material used. For example, thespreading of a material made from carbon fiber is much greater than thatof a linen fiber.

The spreading also depends on the number of fibers in the roving, theiraverage diameter and their cohesion due to the sizing.

The diameter of said at least one compression roller is from 3 mm to 500mm, preferably from 10 mm to 100 mm, in particular from 20 mm to 60 mm.

Below 3 mm, the deformation of the fiber caused by the compressionroller is too great.

Advantageously, the compression roller is cylindrical and not ribbed,and is in particular metallic.

When the supporting part is at least one compression roller, accordingto a first variant, a single compression roller is present in the tankand said pre-impregnation is done at the angle α″₁ formed by saidroving(s) between the inlet of said compression roller and the verticaltangent at said compression roller.

The angle α″₁ formed by said roving(s) between the inlet of saidcompression roller and the vertical tangent to said compression rollerallows the formation of an area in which the powder will concentrate,thus leading to a “corner effect” that, with the simultaneous spreadingof the roving by said compression roller, allows a pre-impregnation overa greater roving width and therefore an improved pre-impregnationcompared to the techniques of the improved background art.

Advantageously, the angle α″₁ is from 0 to 89°, preferably from 5° to85°, preferably from 5° to 45°, preferably from 5° to 30°.

Nevertheless, an angle α₁ from 0 to 5° can cause risks of mechanicalstress, which will lead to breaking of the fibers, and an angle α″₁ from85° to 89° will not create enough mechanical force to create the “cornereffect”.

A value of the angle α₁ equal to 0° therefore corresponds to a verticalfiber. It is clear that the height of the cylindrical compression rolleris adjustable, thus making it possible to position the fiber vertically.

It would not be outside the scope of the invention if the wall of thetank was pierced so as to be allow the exit of the roving.

Advantageously, the inlet edge of the tank (23 a) is equipped with aroller, in particular cylindrical and rotating, on which said roving(s)pass(es), thus leading to spreading prior to the pre-impregnation.

In one embodiment, the spreading is initiated at the inlet edge of thetank (23 a) and continues at said supporter(s) (E′) defined hereinabove.

In another embodiment, one or more supporters (E″) are present upstreamfrom the tank comprising the fluidized bed at which the spreading isinitiated.

The supporters (E″) are as defined for (E′).

Advantageously, the spreading is initiated at the supporter(s) (E″)defined hereinabove and optionally continues at the inlet edge of thetank, then at said supporter(s) (E′) defined hereinabove.

The spreading is then maximal after passage at the compression roller(s)(E′).

Advantageously, the spreading percentage of said roving(s) between theinlet of the supporters (E″) and the outlet of the tank is between 1%and 1000%, preferably from 100% to 800%, preferably from 200% to 800%,preferably from 400% to 800%.

FIG. 12 describes, but is not limited to, an embodiment with a singlecompression roller, with a tank (30) comprising a spray gun (31) forpowder (32) and in which a single cylindrical compression roller (33) ispresent and showing the angle α″₁.

The arrows at the fiber indicate the passage direction of the fiber.

Advantageously, the level of said powder in said tank is at leastlocated at mid-height of said compression roller.

It is clear that the “corner effect” caused by the angle α₁ favors thepre-impregnation on one face, but the spreading of said roving obtainedowing to the compression roller also makes it possible to havepre-impregnation on the other face of said roving. In other words, saidpre-impregnation is favored on one face of said roving(s) at the angleα″₁ formed by said roving(s) between the inlet of said at least onecompression roller R″₁ (33) and the vertical tangent at said compressionroller R″₁, but the spreading also makes it possible to pre-impregnatethe other face.

The angle α″₁ is as defined above.

The spreading of said roving allows a pre-impregnation of said roving.

According to a second variant, when the supporting part is at least onecompression roller, then two compression rollers R″₁ and R″₂ are in saidtank and said pre-impregnation is done at the angle α₁ formed by saidroving(s) between the inlet of said compression roller R″₁ and thevertical tangent to said compression roller R″₁ and/or at the angle α″₂formed by said roving(s) between the inlet of said compression rollerR″₂ and the vertical tangent to said compression roller R″₂, saidcompression roller R″₁ preceding said compression roller R″₂ and saidroving(s) being able to pass above (FIGS. 13 and 14) or below (FIGS. 15and 16) the roller R″₂.

Advantageously, the two compression rollers have identical or differentshapes and are chosen from among a convex, concave or cylindrical shape.

Advantageously, the two compression rollers are identical andcylindrical, non-ribbed, and in particular metallic.

The diameter of the two compression rollers can also be identical ordifferent and is as defined above.

Advantageously, the diameter of the two compression rollers isidentical.

The two compression rollers R″₁ and R″₂ can be at the same levelrelative to one another and relative to the bottom of the tank (FIGS. 14and 15) or offset relative to one another and relative to the bottom ofthe tank, the height of the compression roller R″₁ being higher or lowerthan that of the compression roller R″₂ relative to the bottom of thetank (FIGS. 13 and 16).

Advantageously, when the two rollers are at different heights and theroving passes above the roller R″₂, α″₂ is then from 0 to 90°.

Advantageously, said pre-impregnation is then done at the angle α₁formed by said roving(s) between the inlet of said compression rollerR″₁ in the vertical tangent to said compression roller on a face of saidroving and the angle α″₂ formed by said roving(s) between the inlet ofsaid compression roller R″₂ and the vertical tangent to said compressionroller R″₂ on the opposite face of said roving, which is obtained bypassing above the roller R″₂.

Advantageously, said roving in this embodiment is subject to spreadingat each angle α″₁ and α″₂.

FIG. 14 describes, but is not limited to, an embodiment with twocompression rollers R″₁ and R″₂, R″₁ preceding R″₂, with a tank (30)comprising a powder (32) spray gun (31) in which the two cylindricalcompression rollers, at the same level and side by side, are present andshowing the case where said roving(s) come out between said compressionrollers R″₁ and R″₂.

In this case, the angle α″₂ is equal to 0 and said roving(s) pass abovethe roller R″₂.

The arrows at the fiber indicate the passage direction of the fiber.

Alternatively, said roving(s) pass(es) at the inlet between saidcompression rollers R″₁ and R″₂ and come(s) out after having been incontact with part or all of the surface of said compression roller R″₂.

Advantageously, said roving(s) is (are) in contact at the inlet withpart or all of the surface of said compression roller R″₁ and come(s)out outside the compression roller R″₂ after having been in contact withpart or all of the surface of said compression roller R″₂, beneath theroller R″₂, the angle α″₂ being formed by said roving(s) between theinlet of said compression roller R″₂ and the vertical tangent to saidcompression roller R″₂. In this case, the angle α″₂=90°.

Said pre-impregnation is therefore done at the angle α₁ formed by saidroving(s) between the inlet of said compression roller R″₁ in thevertical tangent to said compression roller on a face of said roving andthe angle α″₂ formed by said roving(s) between the inlet of saidcompression roller R″₂ and the vertical tangent to said compressionroller R″₂ on the same face of said roving, but the spreading also makesit possible to pre-impregnate the other face.

Advantageously, said roving in this embodiment is subject to spreadingat each angle α″₁ and α″₂.

FIG. 15 shows an exemplary embodiment with two compression rollers R″₁and R″₂ at the same level with respect to one another.

According to another embodiment of the second variant, when twocompression rollers are present, then the distance between the twocompression rollers R″₁ and R″₂ is from 0.15 mm to the length equivalentto the maximum dimension of the tank, preferably from 10 mm to 50 mm,and the height difference between the two compression rollers R″₁ andR″₂ is from 0 to the height corresponding to the maximum height of thetank subtracted from the diameters of the two compression rollers,preferably from 0.15 mm to the height corresponding to the maximumheight of the tank subtracted from the diameters of the two compressionrollers, more preferably a height difference between 10 mm and 300 mm,R″₂ being the upper compression roller.

FIG. 16 describes, but is not limited to, an embodiment with twocompression rollers R″₁ and R″₂, R″₁ preceding R″₂, with a tank (30)comprising a powder (32) spray gun (31) in which the two cylindricalcompression rollers at different levels are present and showing theangle α″₁ and α″₂.

The spray flow rate of said powder by each gun on said fibrous materialis identical or different, in particular identical.

The diameter of the compression rollers R″₁ and R″₂ is shown asidentical in FIGS. 13, 14, 15 and 16, but the diameter of eachcylindrical compression roller can be different, the diameter of thecompression roller R″₁ being able to be larger or smaller than that ofthe compression roller R″₂ in the range as defined above.

Advantageously, the diameter of the two compression rollers isidentical.

It would not be going beyond the scope of the invention if thecompression roller R″₁ was larger than the compression roller R″₂.

According to a third variant, when two compression rollers are presentand at different levels, then at least one third compression roller R″₃is also present and located between the compression rollers R″₁ and R″₂in the height direction (FIG. 17). Each compression roller comprises apowder (32) spray gun (31) and the spray flow rate of said powder byeach gun on said fibrous material of the roller inlet is identical ordifferent, in particular identical.

Advantageously, said roving(s) is (are) in contact at the inlet withpart or all of the surface of said compression roller R″₁, then withpart or all of the surface of said compression roller R″₃, and come(s)out after having been in contact with part or all of the surface of saidcompression roller R″₂.

Advantageously, said pre-impregnation is done on a face of saidroving(s) at the angle α₁ formed by said roving(s) between the inlet ofsaid at least one compression roller R″₁ and the vertical tangent tosaid compression roller R″₁ as well as at the angle α″₃ formed by saidroving(s) and the vertical tangent to said compression roller R″₃ and onthe other face at the angle α₂ formed by said roving(s) and the verticaltangent to said compression roller R″₂.

Advantageously, when two compression rollers are present at differentlevels and at least one third compression roller R″₃ is also present,then the angle α′₂ formed by said roving(s) between the inlet of said atleast one compression roller R″₂ and the vertical tangent to saidcompression roller R″₂ is from 180° to 45°, in particular from 120° to60.

Advantageously, the angle α″₃ is from 0° to 180°, advantageously from45° to 135°.

FIG. 17 describes an embodiment, without being limited thereto, with atank (30) comprising two compression rollers R″₁ and R″₂, R″₁ precedingR″₂, and a third compression roller R″₃ and showing the angles α″₁, α″₂and α″₃.

The diameter of the compression rollers R″₁, R″₂ and R″₃ is shown asidentical in FIG. 17, but the diameter of each cylindrical compressionroller can be different, or two compression rollers can have the samediameter and the third can have a different, larger or smaller diameter,in the range as defined above.

Advantageously, the diameter of the three compression rollers isidentical.

Advantageously, in this third variant, a second control of the spreadingof said roving(s) is done at the compression roller R″₃ and a thirdcontrol of the spreading is done at the compression roller R″₃.

The spraying flow rate in this third variant is as defined above.

It would not be outside the scope of the invention if, in this thirdvariant, said roving(s) is(are) in contact at the inlet with part or allof the surface of said compression roller R″₁, then with part or all ofthe surface of said compression roller R″₂, and come(s) out after havingbeen in contact with part or all of the surface of said compressionroller R″₃.

Advantageously, in another variant, six to ten rollers are present andat the same level.

Advantageously, the spraying flow rate in the tank is from 10 g/min to400 g/min, in particular from 20 to 150 g/min.

Advantageously, the volume diameter D90 of the particles ofthermoplastic polymer powder is from 30 to 500 μm, advantageously from80 to 300 μm.

Advantageously, the volume diameter D10 of the particles ofthermoplastic polymer powder is from 5 to 200 μm, advantageously from 15to 100 μm.

Advantageously, the volume diameter of the particles of thermoplasticpolymer powder is in the ratio D90/D10, or from 1.5 to 50,advantageously from 2 to 10.

Advantageously, the average volume diameter D50 of the particles ofthermoplastic polymer powder is from 10 to 300 μm, in particular from 30to 200 μm, more particularly from 45 to 200 μm.

The volume diameters of the particles (D10, D50 and D90) are definedaccording to standard ISO 9276:2014.

“D50” corresponds to the average diameter by volume, that is to say, thevalue of the particle size that divides the examined population ofparticles exactly in half.

“D90” corresponds to the value at 90% of the cumulative curve of theparticle size distribution by volume. “D10” corresponds to the size of10% of the volume of the particles. According to another embodiment ofthe method according to the invention, a creel is present before thetank to control the tension of said roving(s) at the inlet of the tank.

Optionally, in the method according to the invention, one or moresupporters are present after the tank.

Optionally, a differential voltage is applied between the inlet and theoutlet of the tank used for the pre-impregnation step using a brake atthe outlet of said tank.

Heating Step:

A first heating step can immediately follow the pre-impregnation step,or then other steps can take place between the pre-impregnation step andthe heating step and irrespective of the system selected to perform thepre-impregnation step, and in particular with a system chosen from amonga fluidized bed, a spray gun and the molten route, in particular at ahigh speed, in particular a fluidized bed.

Nevertheless, the first heating step implemented by a heating systemprovided with at least one supporting part (E) does not correspond to aheating calendar, and at least one heating system is always done beforethe calendaring step, which is necessary to smooth and shape the ribbon.

Advantageously, said first heating step immediately follows thepre-impregnation step. The expression “immediately follows” means thatthere is no intermediate step between the pre-impregnation step and saidheating step.

Advantageously, a single heating step is done, immediately following thepre-impregnation step.

Advantageously, said at least one heating system is chosen from aninfrared bulb, a UV bulb and convection heating.

The fibrous material being in contact with the supporter(s) and theheating system, and the supporter being conductive, the heating systemtherefore also works by conduction.

Advantageously, said at least one heating system is chosen from aninfrared bulb.

Advantageously, said at least one supporting part (E) is a compressionroller R′_(i) with a convex, concave or cylindrical shape.

It should be noted that the compression rollers corresponding to thesupporting parts (E) and (E″) can be identical or different whether interms of the material or shape and its characteristics (diameter,length, width, height, etc. as a function of the shape).

The convex shape is favorable to the spreading, while the concave shapeis unfavorable to the spreading, although it nevertheless occurs.

The at least one supporting part (E) can also have an alternating convexand concave shape. In this case, the passage of the roving over a convexcompression roller causes the spreading of said roving, then the passageof the roving over a concave compression roller causes the retraction ofthe roving, and so forth, making it possible, if needed, to improve thehomogeneity of the impregnation, in particular to the core.

The expression “compression roller” means that the roving that passesbears partially or wholly on the surface of said compression roller,which causes the spreading of said roving.

The rollers can be free (rotating) or stationary. They can be smooth,striated or grooved.

Advantageously, the rollers are cylindrical and striated. When therollers are striated, two striations can be present in oppositedirections from one another starting from the center of said roller,thus allowing the separation of the rovings toward the outside of theroller or in opposite directions from one another starting from theoutside of said roller, thus making it possible to bring the rovingsback toward the center of the roller.

Whatever the system used for the pre-impregnation step, a firstspreading occurs during this step, in particular if the pre-impregnationstep is done with the use of supporting parts (E′), such as in afluidized bed with at least one supporter as described above.

A first spreading of the roving occurs at said compression rollerscorresponding to the supporting parts (E′) with “corner effect” due tothe partial or complete passage of said roving over said supportingpart(s) (E′) and a second spreading occurs during the heating step, atsaid compression rollers corresponding to the supporting parts (E) dueto the partial or complete passage of said roving over said supportingpart(s) (E). This second spreading is preceded, during the passage ofthe roving in the heating system, before its partial or complete passageover said supporting part(s) (E), by a retraction of the roving due tothe melting of the polymer on said roving.

This second spreading combined with the melting of said polymer matrixby the heating system and the retraction of the roving, make it possibleto homogenize the pre-impregnation and thus to finalize the impregnationand to thus have an impregnation to the core and to have a high fiberrate by volume, in particular constant in at least 70% of the volume ofthe strip or ribbon, in particular in at least 80% of the volume of thestrip or ribbon, in particular in at least 90% of the volume of thestrip or ribbon, more particularly in at least 95% of the volume of thestrip or ribbon, as well as to decrease the porosity.

The spreading depends on the fibrous material used. For example, thespreading of a material made from carbon fiber is much greater than thatof a linen fiber.

The spreading also depends on the number of fibers in the roving, theiraverage diameter and their cohesion due to the sizing.

The diameter of said at least one compression roller (supporter (E)) isfrom 3 mm to 100 mm, preferably from 3 mm to 20 mm, in particular from 5mm to 10 mm.

Below 3 mm, the deformation of the fiber caused by the compressionroller is too great.

Advantageously, the compression roller is cylindrical and not ribbed,and is in particular metallic.

Advantageously, said at least one supporting part (E) is made up of atleast 1 cylindrical compression roller.

Advantageously, said at least one supporting part (E) is made up of 1 to15 cylindrical compression rollers (R′₁ to R′₁₅), preferably 3 to 15compression rollers (R′₃ to R′₁₅), in particular 6 to 10 compressionrollers (R′₆ to R′₁₀).

It is clear that irrespective of the number of supporting parts (E)present, they are all located or comprised in the environment of theheating system, that is to say, they are not outside the heating system.

According to a first variant, said at least one supporting part (E) ismade up of a single compression roller, in particular cylindrical.

Advantageously, said roving(s) form(s) an angle α′₁ of 0.1 to 89°, inparticular of 5 to 75°, in particular of 10 to 45° with a firstcompression roller R′₁ and the horizontal tangent to said compressionroller R′₁, said roving(s) expanding in contact with said compressionroller R′₁.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₁ of more than 89° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₁, this means that theroving has performed at least one complete revolution of said roller.

According to a second variant, said at least one supporting part (E) ismade up of two compression rollers, in particular cylindrical.

Advantageously, said roving(s) form(s) an angle α′_(i) of 0 to 180°, inparticular of 5 to 75°, in particular of 10 to 45° with a firstcompression roller R′₁ and the horizontal tangent to said compressionroller R′₁, said roving(s) expanding in contact with said compressionroller R′₁.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₁ of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₁, this means that theroving has performed at least one complete revolution of said roller.

Advantageously, a second compression roller R′₂ is present after saidfirst compression roller R′₁, said roving(s) forming an angle α′₂ of 0to 180°, in particular of 5 to 75°, in particular of 10 to 45° with saidsecond compression roller R′₂ and the horizontal tangent to saidcompression roller R′₂, said roving(s) expanding in contact with saidcompression roller.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₂ of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₂, this means that theroving has performed at least one complete revolution of said roller.

The roving passes below the roller R′₁, then above the roller R′₂. It isclear that the passage of the roving above the roller R′₁, then belowthe roller R′₂ is also an embodiment of the invention.

The roller R′₂ can be located above the roller R′₁, said roller R′₁preceding said roller R′₂.

It is likewise obvious that the roller R′₂ can be located below theroller RT₁.

The height difference between the roller R′₁ and the roller R′₂ isgreater than or equal to 0.

Advantageously, the height difference between the roller R′₁ and theroller R′₂ is between 1 and 20 cm, preferably from 2 to 15 cm, and inparticular from 3 to 10 cm.

Advantageously, the two rollers are at the same level and have the samediameter, and the height difference is then nil.

The distance between the two rollers is between 1 and 20 cm, preferablyfrom 2 to 15 cm, in particular from 3 to 10 cm.

According to a third variant, said at least one supporting part (E) ismade up of 3 compression rollers, in particular cylindrical.

Advantageously, said roving(s) form(s) an angle α′₁ of 0.1 to 89°, inparticular of 5 to 75°, in particular of 10 to 45° with a firstcompression roller R′₁ and the horizontal tangent to said compressionroller R′₁, said roving(s) expanding in contact with said firstcompression roller.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₁ of more than 89° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₁, this means that theroving has performed at least one complete revolution of said roller.

Advantageously, the second roller is present after said first roller,said roving(s) forming an angle α′₂ of 0 to 180°, in particular of 5 to75°, in particular of 10 to 45° with the second compression roller R′₂and the horizontal tangent to said compression roller R′₂, saidroving(s) expanding in contact with said compression roller.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₂ of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₂, this means that theroving has performed at least one complete revolution of said roller.

Advantageously, the third compression roller R′₃ is present after saidsecond compression roller R′₂, said roving(s) forming an angle α′₃ of 0to 180°, in particular of 5 to 75°, in particular of 10 to 45° with saidthird compression roller R′₃ and the horizontal tangent to saidcompression roller R′₃, said roving(s) expanding in contact with saidcompression roller R′₃.

It would not be outside the scope of the invention if the roving were toform an angle with said horizontal tangent to said compression rollerR′₃ of more than 180° to 360° (modulo 360°).

In the event the roving forms an angle of at least 360° with saidhorizontal tangent to said compression roller R′₃, this means that theroving has performed at least one complete revolution of said roller.

The roving passes below the roller R′₁, then above the roller R′₂, andnext below the roller R′₃.

It is clear that the passage of the roving above the roller R′₁, thenbelow the roller R′₂ and next above the roller R′₃ is also an embodimentof the invention.

The three rollers can be at the same level, but advantageously, theroller R′₂ is located above the roller R′₁, and the roller R′₃ islocated below the roller R′₂, said roller R′₁ preceding said roller R′₂,which in turn precedes R′₃.

All relative geometric positions between the three rollers are possible.

The height difference between the lowest roller and the highest rolleris greater than or equal to 0.

Advantageously, the height difference between each of the three rollersis between 1 and 20 cm, preferably from 2 to 15 cm, in particular from 3to 10 cm.

The distance between each of the three rollers is from 1 to 20 cm,preferably from 2 to 15 cm, in particular from 3 to 10 cm.

Advantageously, the roller R′₁ precedes the roller R′₃ and are at thesame level and the roller R′₂ is located between the roller R′₁ and theroller R′₃ and is located above the other two rollers.

FIG. 1 shows an exemplary heating system having three compressionrollers.

The length I between the inlet of the heating system and the firstroller R′₁ is variable as a function of the polymer used and the passagespeed of the strip.

I therefore represents the length sufficient for the polymer to melt, atleast partially, particularly completely, at the inlet of the firstroller.

In one embodiment, four (4) to fifteen (15) rollers can be present.

In general, the angle(s) α′_(4-i) (i being from 4 to 15) formed by saidroving(s) with the rollers R′₄₋₁ is(are) from 0 to 180°, in particularfrom 5 to 75°, particularly from 10 to 45°.

In general, the height difference between each roller R′_(i) and betweenthe lowest roller and the highest roller is greater than or equal to 0.

Advantageously, the height difference between each of the rollers R′_(i)is between 1 and 20 cm, preferably from 2 to 15 cm, in particular from 3to 10 cm.

In general, the distance between each of the rollers R′_(i) is from 1 to20 cm, preferably from 2 to 15 cm, in particular from 3 to 10 cm.

Advantageously, the spreading percentage during the heating step betweenthe inlet of the first compression roller R′₁ and the outlet of the lastcompression roller R′_(i) is about 0 to 300%, in particular 0 to 50%.

Advantageously, the spreading percentage during the heating step betweenthe inlet of the first compression roller R′₁ and the outlet of the lastcompression roller R′_(i) is about 1 to 50%.

Advantageously, said thermoplastic polymer is a nonreactivethermoplastic polymer. The heating system therefore allows the meltingof said thermoplastic polymer after pre-impregnation, as describedhereinabove.

Advantageously, said thermoplastic polymer is a reactive pre-polymercapable of reacting with itself or with another pre-polymer, based onthe chain ends of said pre-polymer, or with another chain extender, saidreactive polymer optionally being polymerized during the heating step.

Depending on the temperature and/or the passage speed of the roving, theheating system allows the melting of said thermoplastic pre-polymerafter pre-impregnation as described hereinabove without polymerizationof said pre-polymer with itself or with a chain extender or of saidpre-polymers amongst themselves.

The fiber level in the impregnated fibrous material is set during theheating step and advantageously it is from 45 to 65% by volume,preferably from 50 to 60% by volume, in particular from 54 to 60%.

Below 45% fibers, the reinforcement is not of interest regarding themechanical properties.

Above 65%, the limitations of the method are reached and the mechanicalproperties are lost again.

Advantageously, the porosity level in said impregnated fibrous materialis less than 10%, in particular less than 5%, particularly less than 2%.

A second heating step can be carried out after the calendaring stepbelow.

This second heating step makes it possible to correct any defects, inparticular in homogeneity, that may remain after the first heating step.

It is done with the same system as for the first step.

Advantageously, the heating system of this second step is made up of tworollers.

Optionally, said pre-impregnation and impregnation steps are completedby a step for molding in a nozzle regulated at a constant temperature,said molding step being done before said calendaring step. Optionally,this nozzle is a crosshead-die extrusion nozzle and makes it possible tocover said single roving or said plurality of parallel rovings afterimpregnation by the powder, said covering step being done before saidcalendaring step, with a molten thermoplastic polymer, which may beidentical to or different from said pre-impregnation polymer, saidmolten polymer preferably being of the same nature as saidpre-impregnation polymer.

To that end, a covering device is connected to the outlet of the heatingsystem that may include a covering crosshead-die head, as is alsodescribed in patent EP0406067. The covering polymer may be identical toor different from the polymer powder in the tank. Preferably, it is ofthe same nature. Such covering makes it possible not only to completethe impregnation step of the fibers in order to obtain a final volumerate of polymer in the desired range and to prevent the presence, on thesurface of the impregnated roving, of a fiber level that is locally toohigh, which would be detrimental to the welding of the tapes during themanufacturing of the composite part, in particular to obtain “ready touse” fibrous materials of good quality, but also to improve theperformance of the obtained composite material.

Shaping Step:

Optionally, a step for shaping of the roving or parallel rovings of saidimpregnated fibrous material is done.

A calendaring system as described in WO 2015/121583 can be used.

Advantageously, it is done by calendaring using at least one heatingcalendar in the form of a single unidirectional ribbon or a plurality ofparallel unidirectional ribbons with, in the latter case, said heatingcalendar including a plurality of calendaring grooves, preferably up to200 calendaring grooves, in accordance with the number of said ribbonsand with a pressure and/or separation between the rollers of saidcalendar regulated by a governing system.

This step is always done after the heating step if there is only one orbetween the first heating step and the second heating step when the twocoexist.

Advantageously, the calendaring step is done using a plurality ofheating calendars, mounted in parallel and/or in series relative to thepassage direction of the fiber rovings.

Advantageously, said heating calendar(s) comprise(s) an integratedinduction or microwave heating system, preferably microwave, coupledwith the presence of carbon fillers in said thermoplastic polymer ormixture of thermoplastic polymers.

According to another embodiment, a belt press is present between theheating system and the calendar.

According to still another embodiment, a heating nozzle is presentbetween the heating system and the calendar.

According to another embodiment, a belt press is present between theheating system and the calendar and a heating nozzle is present betweenthe belt press and the calendar.

According to another aspect, the present invention relates to aunidirectional ribbon of impregnated fibrous material, in particular aribbon wound on a spool, characterized in that it is obtained using amethod as defined hereinabove.

Advantageously, said ribbon has a width (I) and thickness (ep) suitablefor robot application in the manufacture of three-dimensionalworkpieces, without the need for slitting, and preferably has a width(I) of at least 5 mm and up to 400 mm, preferably between 5 and 50 mm,and even more preferably between 5 and 15 mm.

Advantageously, the thermoplastic polymer of said ribbon is a polyamideas defined hereinabove.

Advantageously, it is in particular selected from an aliphatic polyamidesuch as PA 6, PA 11, PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA1012, PA 11/1010 or PA 12/1010 or a semi-aromatic polyamide such as PAMXD6 and PA MXD10 or chosen from PA 6/6T, PA 6I/6T, PA 66/6T, PA 11/10T,PA 11/6T/10T, PA MXDT/10T, PA MPMDT/10T, PA BACT/6T, PA BACT/10T and PABACT/10T/6T, PVDF, PEEK, PEKK and PEI or a mixture thereof.

According to another aspect, the present invention relates to the use ofa method as defined hereinabove, for the manufacture of calibratedribbons suitable for the manufacture of three-dimensional compositeparts, by the automatic laying of the said ribbons by means of a robot.

According to still another aspect, the present invention relates to theuse of a ribbon of impregnated fibrous material, as defined hereinabove,in the manufacture of three-dimensional composite parts.

Advantageously, said manufacturer of said composite parts relates to thefields of transportation, in particular automotive, oil and gas, inparticular offshore, gas storage, aeronautics, naval, railways;renewable energies, in particular wind energy, hydro turbines, energystorage devices, solar panels; thermal protection panels; sports andleisure, health and medical and electronics.

According to another aspect, the present invention relates to athree-dimensional composite part, characterized in that it results fromthe use of at least one unidirectional ribbon of impregnated fibrousmaterial as defined hereinabove.

Advantageous Embodiments

Fluidized Bed Combined with One or Two Heating Steps

Advantageously, the fibrous material is selected from carbon fiber andglass fiber.

Advantageously, the thermoplastic pre-polymer used to impregnate thecarbon fiber is selected from a polyamide, in particular an aliphaticpolyamide such as PA 11, PA 12, PA 11/1010 and PA 12/1010, asemi-aromatic polyamide, in particular PA 11/10T, PA 11/6T/10T, PAMXDT/10T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/10T/6T, PA MXD6and PA MXD10, PEEK, PEKK and PEI or a mixture thereof.

Advantageously, the thermoplastic pre-polymer used to impregnate theglass fiber is selected from a polyamide, in particular an aliphaticpolyamide such as PA 11, PA 12, PA 11/1010 and PA 12/1010, asemi-aromatic polyamide, in particular PA 11/10T, PA 11/6T/10T, PAMXDT/10T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/10T/6T, PA MXD6and PA MXD10, PEEK, PEKK and PEI or a mixture thereof.

Table 1 below shows advantageous embodiments according to the inventivemethod in which the pre-impregnation step is done in a tank comprising,for a carbon fiber or glass fiber roving with one or more non-ribbedcylindrical compression roller(s):

TABLE I Fibrous Number of Embodiment material compression ResidenceAngle α₁ no. (fiber type) Polymer rollers time (s) (°) 1 CarbonPolyamide 1 0.1 to 5 5 to 85 2 Carbon Polyamide 1 0.1 to 5 5 to 45 3Carbon Polyamide 1 0.1 to 5 5 to 30 4 Carbon Polyamide 1 0.1 to 3 5 to85 5 Carbon Polyamide 1 0.1 to 3 5 to 45 6 Carbon Polyamide 1 0.1 to 3 5to 30 7 Carbon Polyamide 2 0.1 to 5 5 to 85 8 Carbon Polyamide 2 0.1 to5 5 to 45 9 Carbon Polyamide 2 0.1 to 5 5 to 30 10 Carbon Polyamide 20.1 to 3 5 to 85 11 Carbon Polyamide 2 0.1 to 3 5 to 45 12 CarbonPolyamide 2 0.1 to 3 5 to 30 13 Carbon Polyamide 3 0.1 to 5 5 to 85 14Carbon Polyamide 3 0.1 to 5 5 to 45 15 Carbon Polyamide 3 0.1 to 5 5 to30 16 Carbon Polyamide 3 0.1 to 3 5 to 85 17 Carbon Polyamide 3 0.1 to 35 to 45 18 Carbon Polyamide 3 0.1 to 3 5 to 30 19 Carbon PEKK 1 0.1 to 55 to 85 20 Carbon PEKK 1 0.1 to 5 5 to 45 21 Carbon PEKK 1 0.1 to 5 5 to30 22 Carbon PEKK 1 0.1 to 3 5 to 85 23 Carbon PEKK 1 0.1 to 3 5 to 4524 Carbon PEKK 1 0.1 to 3 5 to 30 25 Carbon PEKK 2 0.1 to 5 5 to 85 26Carbon PEKK 2 0.1 to 5 5 to 45 27 Carbon PEKK 2 0.1 to 5 5 to 30 28Carbon PEKK 2 0.1 to 3 5 to 85 29 Carbon PEKK 2 0.1 to 3 5 to 45 30Carbon PEKK 2 0.1 to 3 5 to 30 31 Carbon PEKK 3 0.1 to 5 5 to 85 32Carbon PEKK 3 0.1 to 5 5 to 45 33 Carbon PEKK 3 0.1 to 5 5 to 30 34Carbon PEKK 3 0.1 to 3 5 to 85 35 Carbon PEKK 3 0.1 to 3 5 to 45 36Carbon PEKK 3 0.1 to 3 5 to 30 37 Carbon PEI 1 0.1 to 5 5 to 85 38Carbon PEI 1 0.1 to 5 5 to 45 39 Carbon PEI 1 0.1 to 5 5 to 30 40 CarbonPEI 1 0.1 to 3 5 to 85 41 Carbon PEI 1 0.1 to 3 5 to 45 42 Carbon PEI 10.1 to 3 5 to 30 43 Carbon PEI 2 0.1 to 5 5 to 85 44 Carbon PEI 2 0.1 to5 5 to 45 45 Carbon PEI 2 0.1 to 5 5 to 30 46 Carbon PEI 2 0.1 to 3 5 to85 47 Carbon PEI 2 0.1 to 3 5 to 45 48 Carbon PEI 2 0.1 to 3 5 to 30 49Carbon PEI 3 0.1 to 5 5 to 85 50 Carbon PEI 3 0.1 to 5 5 to 45 51 CarbonPEI 3 0.1 to 5 5 to 30 52 Carbon PEI 3 0.1 to 3 5 to 85 53 Carbon PEI 30.1 to 3 5 to 45 54 Carbon PEI 3 0.1 to 3 5 to 30 55 Carbon PEI 1 0.1 to5 5 to 85 56 Carbon PEI 1 0.1 to 5 5 to 45 57 Carbon PEI 1 0.1 to 5 5 to30 58 Carbon PEI 1 0.1 to 3 5 to 85 59 Carbon PEI 1 0.1 to 3 5 to 45 60Carbon PEI 1 0.1 to 3 5 to 30 61 Carbon PEI 2 0.1 to 5 5 to 85 62 CarbonPEI 2 0.1 to 5 5 to 45 63 Carbon PEI 2 0.1 to 5 5 to 30 64 Carbon PEI 20.1 to 3 5 to 85 65 Carbon PEI 2 0.1 to 3 5 to 45 66 Carbon PEI 2 0.1 to3 5 to 30 67 Carbon PEI 3 0.1 to 5 5 to 85 68 Carbon PEI 3 0.1 to 5 5 to45 69 Carbon PEI 3 0.1 to 5 5 to 30 70 Carbon PEI 3 0.1 to 3 5 to 85 71Carbon PEI 3 0.1 to 3 5 to 45 72 Carbon PEI 3 0.1 to 3 5 to 30 73 GlassPolyamide 1 0.1 to 5 5 to 85 74 Glass Polyamide 1 0.1 to 5 5 to 45 75Glass Polyamide 1 0.1 to 5 5 to 30 76 Glass Polyamide 1 0.1 to 3 5 to 8577 Glass Polyamide 1 0.1 to 3 5 to 45 78 Glass Polyamide 1 0.1 to 3 5 to30 79 Glass Polyamide 2 0.1 to 5 5 to 85 80 Glass Polyamide 2 0.1 to 5 5to 45 81 Glass Polyamide 2 0.1 to 5 5 to 30 82 Glass Polyamide 2 0.1 to3 5 to 85 83 Glass Polyamide 2 0.1 to 3 5 to 45 84 Glass Polyamide 2 0.1to 3 5 to 30 85 Glass Polyamide 3 0.1 to 5 5 to 85 86 Glass Polyamide 30.1 to 5 5 to 45 87 Glass Polyamide 3 0.1 to 5 5 to 30 88 GlassPolyamide 3 0.1 to 3 5 to 85 89 Glass Polyamide 3 0.1 to 3 5 to 45 90Glass Polyamide 3 0.1 to 3 5 to 30 91 Glass PEKK 1 0.1 to 5 5 to 85 92Glass PEKK 1 0.1 to 5 5 to 45 93 Glass PEKK 1 0.1 to 5 5 to 30 94 GlassPEKK 1 0.1 to 3 5 to 85 95 Glass PEKK 1 0.1 to 3 5 to 45 96 Glass PEKK 10.1 to 3 5 to 30 97 Glass PEKK 2 0.1 to 5 5 to 85 98 Glass PEKK 2 0.1 to5 5 to 45 99 Glass PEKK 2 0.1 to 5 5 to 30 100 Glass PEKK 2 0.1 to 3 5to 85 101 Glass PEKK 2 0.1 to 3 5 to 45 102 Glass PEKK 2 0.1 to 3 5 to30 103 Glass PEKK 3 0.1 to 5 5 to 85 104 Glass PEKK 3 0.1 to 5 5 to 45105 Glass PEKK 3 0.1 to 5 5 to 30 106 Glass PEKK 3 0.1 to 3 5 to 85 107Glass PEKK 3 0.1 to 3 5 to 45 108 Glass PEKK 3 0.1 to 3 5 to 30 109Glass PEI 1 0.1 to 5 5 to 85 110 Glass PEI 1 0.1 to 5 5 to 45 111 GlassPEI 1 0.1 to 5 5 to 30 112 Glass PEI 1 0.1 to 3 5 to 85 113 Glass PEI 10.1 to 3 5 to 45 114 Glass PEI 1 0.1 to 3 5 to 30 115 Glass PEI 2 0.1 to5 5 to 85 116 Glass PEI 2 0.1 to 5 5 to 45 117 Glass PEI 2 0.1 to 5 5 to30 118 Glass PEI 2 0.1 to 3 5 to 85 119 Glass PEI 2 0.1 to 3 5 to 45 120Glass PEI 2 0.1 to 3 5 to 30 121 Glass PEI 3 0.1 to 5 5 to 85 122 GlassPEI 3 0.1 to 5 5 to 45 123 Glass PEI 3 0.1 to 5 5 to 30 124 Glass PEI 30.1 to 3 5 to 85 125 Glass PEI 3 0.1 to 3 5 to 45 126 Glass PEI 3 0.1 to3 5 to 30 127 Glass PEI 1 0.1 to 5 5 to 85 128 Glass PEI 1 0.1 to 5 5 to45 129 Glass PEI 1 0.1 to 5 5 to 30 130 Glass PEI 1 0.1 to 3 5 to 85 131Glass PEI 1 0.1 to 3 5 to 45 132 Glass PEI 1 0.1 to 3 5 to 30 133 GlassPEI 2 0.1 to 5 5 to 85 134 Glass PEI 2 0.1 to 5 5 to 45 135 Glass PEI 20.1 to 5 5 to 30 136 Glass PEI 2 0.1 to 3 5 to 85 137 Glass PEI 2 0.1 to3 5 to 45 138 Glass PEI 2 0.1 to 3 5 to 30 139 Glass PEI 3 0.1 to 5 5 to85 140 Glass PEI 3 0.1 to 5 5 to 45 141 Glass PEI 3 0.1 to 5 5 to 30 142Glass PEI 3 0.1 to 3 5 to 85 143 Glass PEI 3 0.1 to 3 5 to 45 144 GlassPEI 3 0.1 to 3 5 to 30

In the embodiments comprising PEKK or PEI, the PEKK can be mixed withPEI and the PEI can be mixed with PEKK in the proportions definedhereinabove.

Advantageously, in the compositions of table I defined hereinabove inwhich two compression rollers are present in the fluidized bed, theroller R₂ is above the roller R₁ with respect to the bottom of the tank,in particular H₂-H₁ is from 1 cm to 30 cm, preferably from 1 to 10 cm,in particular from 1 cm to 3 cm, particularly about 2 cm and the angleα₂ is from 0 to 90°, in particular from 25 to 45° C., particularly from25 to 35° and the roving passes over R₂.

These embodiments correspond to FIG. 5.

Advantageously, in the compositions of table I defined hereinabove inwhich two compression rollers are present in the fluidized bed, theroller R₂ is above the roller R₁ with respect to the bottom of the tank,in particular H₂-H₁ is from 1 cm to 30 cm, particularly about 2 cm andthe angle α₂ is from 90 to 180°, in particular from 115 to 135° C.,particularly from 115 to 125°, and the roving passes below R₂.

Advantageously, the different fibrous materials obtained with theembodiments by pre-impregnation in a fluidized bed of table I nextundergo a heating step directly after the pre-impregnation step with anIR heating system with one, two or three rollers as described in tableII.

TABLE II Embodi- Number of ment Fluidized bed compression Angle α′₁Angle α′₂ Angle α′₃ no. embodiment rollers (°) (°) (°) 145 1 to 144 10.1-89  — — 146 1 to 144 1  5-75 — — 147 1 to 144 1 10-45 — — 148 1 to144 2 0.1-89   0-180 — 149 1 to 144 2 0.1-89   5-75 — 150 1 to 144 20.1-89  10-45 — 151 1 to 144 2  5-75  0-180 — 152 1 to 144 2  5-75  5-75— 153 1 to 144 2  5-75 10-45 — 154 1 to 144 2 10-45  0-180 — 155 1 to144 2 10-45  5-75 — 156 1 to 144 2 10-45 10-45 — 157 1 to 144 3 0.1-89  0-180  0-180 158 1 to 144 3 0.1-89   0-180  5-75 159 1 to 144 3 0.1-89  0-180 10-45 160 1 to 144 3  5-75  0-180  0-180 161 1 to 144 3  5-75 0-180  5-75 162 1 to 144 3  5-75  0-180 10-45 163 1 to 144 3 10-45 0-180  0-180 164 1 to 144 3 10-45  0-180  5-75 165 1 to 144 3 10-45 0-180 10-45 166 1 to 144 3 0.1-89   5-75  0-180 167 1 to 144 3 0.1-89  5-75  5-75 168 1 to 144 3 0.1-89   5-75 10-45 169 1 to 144 3  5-75 5-75  0-180 170 1 to 144 3  5-75  5-75  5-75 171 1 to 144 3  5-75  5-7510-45 172 1 to 144 3 10-45  5-75  0-180 173 1 to 144 3 10-45  5-75  5-75174 1 to 144 3 10-45  5-75 10-45 175 1 to 144 3 0.1-89  10-45  0-180 1761 to 144 3 0.1-89  10-45  5-75 177 1 to 144 3 0.1-89  10-45 10-45 178 1to 144 3  5-75 10-45  0-180 179 1 to 144 3  5-75 10-45  5-75 180 1 to144 3  5-75 10-45 10-45 181 1 to 144 3 10-45 10-45  0-180 182 1 to 144 310-45 10-45  5-75 183 1 to 144 3 10-45 10-45 10-45

Optionally, a second heating step with an IR heating system with one ortwo rollers is done according to table III.

TABLE III Fluidized bed embodiment directly Number of Embodimentfollowed by compression Angle α′₁ Angle α′₂ no. the heating step rollers(°) (°) 184 145 to 183 1 0.1-89  — 185 145 to 183 1  5-75 — 186 145 to183 1 10-45 — 187 145 to 183 2 0.1-89   0-180 188 145 to 183 2 0.1-89  5-75 189 145 to 183 2 0.1-89  10-45 190 145 to 183 2  5-75  0-180 191145 to 183 2  5-75  5-75 192 145 to 183 2  5-75 10-45 193 145 to 183 210-45  0-180 194 145 to 183 2 10-45  5-75 195 145 to 183 2 10-45 10-45

Spraying of the Powder by One (or More) Nozzle(s) or One (or More)Gun(s) by Dry Route in a Tank Combined With One or Two Heating Steps

Advantageously, the fibrous material is selected from carbon fiber andglass fiber.

Advantageously, the thermoplastic polymer used to impregnate the carbonfiber is selected from a polyamide, in particular an aliphatic polyamidesuch as PA 11, PA 12, PA 11/1010 or PA 12/1010, or a semi-aromaticpolyamide, in particular PA MXD6 and PA MXD10, PA 11/10T, PA 11/6T/10T,PA MXDT/10T or PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/10T/6T,PEEK, PEKK and PEI or a mixture thereof.

Advantageously, the thermoplastic polymer used to impregnate the glassfiber is selected from a polyamide, in particular an aliphatic polyamidesuch as PA 11, PA 12, PA 11/1010 or PA 12/1010, or a semi-aromaticpolyamide, in particular PA MXD6 and PA MXD10, PA 11/10T, PA 11/6T/10T,PA MXDT/10T or PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/10T/6T,PEEK, PEKK and PEI or a mixture thereof.

The following table IV shows advantageous embodiments according to theinventive method in which the pre-impregnation step is done by sprayingsaid powder by one (or several) nozzle(s) or one (or several) gun(s) bydry route in a tank comprising, for a carbon fiber or glass fiber rovingwith one or more non-ribbed cylindrical compression roller(s):

TABLE IV Embodi- Fibrous Number of Spraying ment material compressionflow rate Angle α″₁ no. (fiber type) Polymer rollers (g/min) (°) 196Carbon Polyamide 1 10 to 400 5 to 85 197 Carbon Polyamide 1 10 to 400 5to 45 198 Carbon Polyamide 1 10 to 400 5 to 30 199 Carbon Polyamide 1 25to 150 5 to 85 200 Carbon Polyamide 1 25 to 150 5 to 45 201 CarbonPolyamide 1 25 to 150 5 to 30 202 Carbon Polyamide 2 10 to 400 5 to 85203 Carbon Polyamide 2 10 to 400 5 to 45 204 Carbon Polyamide 2 10 to400 5 to 30 205 Carbon Polyamide 2 25 to 150 5 to 85 206 CarbonPolyamide 2 25 to 150 5 to 45 207 Carbon Polyamide 2 25 to 150 5 to 30208 Carbon Polyamide 3 10 to 400 5 to 85 209 Carbon Polyamide 3 10 to400 5 to 45 201 Carbon Polyamide 3 10 to 400 5 to 30 211 CarbonPolyamide 3 25 to 150 5 to 85 212 Carbon Polyamide 3 25 to 150 5 to 45213 Carbon Polyamide 3 25 to 150 5 to 30 214 Carbon PEKK 1 10 to 400 5to 85 215 Carbon PEKK 1 10 to 400 5 to 45 216 Carbon PEKK 1 10 to 400 5to 30 217 Carbon PEKK 1 25 to 150 5 to 85 218 Carbon PEKK 1 25 to 150 5to 45 219 Carbon PEKK 1 25 to 150 5 to 30 220 Carbon PEKK 2 10 to 400 5to 85 221 Carbon PEKK 2 10 to 400 5 to 45 222 Carbon PEKK 2 10 to 400 5to 30 223 Carbon PEKK 2 25 to 150 5 to 85 224 Carbon PEKK 2 25 to 150 5to 45 225 Carbon PEKK 2 25 to 150 5 to 30 226 Carbon PEKK 3 10 to 400 5to 85 227 Carbon PEKK 3 10 to 400 5 to 45 228 Carbon PEKK 3 10 to 400 5to 30 229 Carbon PEKK 3 25 to 150 5 to 85 230 Carbon PEKK 3 25 to 150 5to 45 231 Carbon PEKK 3 25 to 150 5 to 30 232 Carbon PEI 1 10 to 400 5to 85 233 Carbon PEI 1 10 to 400 5 to 45 234 Carbon PEI 1 10 to 400 5 to30 235 Carbon PEI 1 25 to 150 5 to 85 236 Carbon PEI 1 25 to 150 5 to 45237 Carbon PEI 1 25 to 150 5 to 30 238 Carbon PEI 2 10 to 400 5 to 85239 Carbon PEI 2 10 to 400 5 to 45 240 Carbon PEI 2 10 to 400 5 to 30241 Carbon PEI 2 25 to 150 5 to 85 242 Carbon PEI 2 25 to 150 5 to 45243 Carbon PEI 2 25 to 150 5 to 30 244 Carbon PEI 3 10 to 400 5 to 85245 Carbon PEI 3 10 to 400 5 to 45 246 Carbon PEI 3 10 to 400 5 to 30247 Carbon PEI 3 25 to 150 5 to 85 248 Carbon PEI 3 25 to 150 5 to 45249 Carbon PEI 3 25 to 150 5 to 30 250 Carbon PEI 1 10 to 400 5 to 85251 Carbon PEI 1 10 to 400 5 to 45 252 Carbon PEI 1 10 to 400 5 to 30253 Carbon PEI 1 25 to 150 5 to 85 254 Carbon PEI 1 25 to 150 5 to 45255 Carbon PEI 1 25 to 150 5 to 30 256 Carbon PEI 2 10 to 400 5 to 85257 Carbon PEI 2 10 to 400 5 to 45 258 Carbon PEI 2 10 to 400 5 to 30259 Carbon PEI 2 25 to 150 5 to 85 260 Carbon PEI 2 25 to 150 5 to 45261 Carbon PEI 2 25 to 150 5 to 30 262 Carbon PEI 3 10 to 400 5 to 85263 Carbon PEI 3 10 to 400 5 to 45 264 Carbon PEI 3 10 to 400 5 to 30265 Carbon PEI 3 25 to 150 5 to 85 266 Carbon PEI 3 25 to 150 5 to 45267 Carbon PEI 3 25 to 150 5 to 30 268 Glass Polyamide 1 10 to 400 5 to85 269 Glass Polyamide 1 10 to 400 5 to 45 270 Glass Polyamide 1 10 to400 5 to 30 271 Glass Polyamide 1 25 to 150 5 to 85 272 Glass Polyamide1 25 to 150 5 to 45 273 Glass Polyamide 1 25 to 150 5 to 30 274 GlassPolyamide 2 10 to 400 5 to 85 275 Glass Polyamide 2 10 to 400 5 to 45276 Glass Polyamide 2 10 to 400 5 to 30 277 Glass Polyamide 2 25 to 1505 to 85 278 Glass Polyamide 2 25 to 150 5 to 45 279 Glass Polyamide 2 25to 150 5 to 30 280 Glass Polyamide 3 10 to 400 5 to 85 281 GlassPolyamide 3 10 to 400 5 to 45 282 Glass Polyamide 3 10 to 400 5 to 30283 Glass Polyamide 3 25 to 150 5 to 85 284 Glass Polyamide 3 25 to 1505 to 45 285 Glass Polyamide 3 25 to 150 5 to 30 286 Glass PEKK 1 10 to400 5 to 85 287 Glass PEKK 1 10 to 400 5 to 45 288 Glass PEKK 1 10 to400 5 to 30 289 Glass PEKK 1 25 to 150 5 to 85 290 Glass PEKK 1 25 to150 5 to 45 291 Glass PEKK 1 25 to 150 5 to 30 292 Glass PEKK 2 10 to400 5 to 85 293 Glass PEKK 2 10 to 400 5 to 45 294 Glass PEKK 2 10 to400 5 to 30 295 Glass PEKK 2 25 to 150 5 to 85 296 Glass PEKK 2 25 to150 5 to 45 297 Glass PEKK 2 25 to 150 5 to 30 298 Glass PEKK 3 10 to400 5 to 85 299 Glass PEKK 3 10 to 400 5 to 45 300 Glass PEKK 3 10 to400 5 to 30 301 Glass PEKK 3 25 to 150 5 to 85 302 Glass PEKK 3 25 to150 5 to 45 303 Glass PEKK 3 25 to 150 5 to 30 304 Glass PEI 1 10 to 4005 to 85 305 Glass PEI 1 10 to 400 5 to 45 306 Glass PEI 1 10 to 400 5 to30 307 Glass PEI 1 25 to 150 5 to 85 308 Glass PEI 1 25 to 150 5 to 45309 Glass PEI 1 25 to 150 5 to 30 310 Glass PEI 2 10 to 400 5 to 85 311Glass PEI 2 10 to 400 5 to 45 312 Glass PEI 2 10 to 400 5 to 30 313Glass PEI 2 25 to 150 5 to 85 314 Glass PEI 2 25 to 150 5 to 45 315Glass PEI 2 25 to 150 5 to 30 316 Glass PEI 3 10 to 400 5 to 85 317Glass PEI 3 10 to 400 5 to 45 318 Glass PEI 3 10 to 400 5 to 30 319Glass PEI 3 25 to 150 5 to 85 320 Glass PEI 3 25 to 150 5 to 45 321Glass PEI 3 25 to 150 5 to 30 322 Glass PEI 1 10 to 400 5 to 85 323Glass PEI 1 10 to 400 5 to 45 324 Glass PEI 1 10 to 400 5 to 30 325Glass PEI 1 25 to 150 5 to 85 326 Glass PEI 1 25 to 150 5 to 45 327Glass PEI 1 25 to 150 5 to 30 328 Glass PEI 2 10 to 400 5 to 85 329Glass PEI 2 10 to 400 5 to 45 330 Glass PEI 2 10 to 400 5 to 30 331Glass PEI 2 25 to 150 5 to 85 332 Glass PEI 2 25 to 150 5 to 45 333Glass PEI 2 25 to 150 5 to 30 334 Glass PEI 3 10 to 400 5 to 85 335Glass PEI 3 10 to 400 5 to 45 336 Glass PEI 3 10 to 400 5 to 30 337Glass PEI 3 25 to 150 5 to 85 338 Glass PEI 3 25 to 150 5 to 45 339Glass PEI 3 25 to 150 5 to 30

In the embodiments comprising PEKK or PEI, the PEKK can be mixed withPEI and the PEI can be mixed with PEKK in the proportions definedhereinabove.

Advantageously, in the compositions of table IV defined hereinabove inwhich two compression rollers are present in the tank, the roller R″₂ isabove the roller R″₁ with respect to the bottom of the tank, inparticular H₂-H₁ is from 1 cm to 30 cm, preferably from 1 to 10 cm, inparticular from 1 cm to 3 cm, particularly about 2 cm and the angle α″₂is from 0 to 90°, in particular from 25 to 45° C., particularly from 25to 35° and the roving passes over R″₂.

These embodiments correspond to FIG. 13.

Advantageously, in the compositions of table IV defined hereinabove inwhich two compression rollers are present in the fluidized bed, theroller R″₂ is above the roller R″₁ with respect to the bottom of thetank, in particular H₂-H₁ is from 1 cm to 30 cm, particularly about 2 cmand the angle α″₂ is from 90 to 180°, in particular from 115 to 135° C.,particularly from 115 to 125°, and the roving passes below R″₂.

Advantageously, the different fibrous materials obtained with theembodiments by pre-impregnation by spraying said powder by one (or more)nozzle(s) or one (or more) gun(s) by dry route in a tank of table IVnext undergo a heating step directly after the step for impregnationwith an IR heating system with one, two or three rollers as described intable V.

TABLE V Embodi- Number of ment Spraying compression Angle α′₁ Angle α′₂Angle α′₃ no. embodiment rollers (°) (°) (°) 340 1 to 339 1 0.1-89  — —341 1 to 339 1  5-75 — — 342 1 to 339 1 10-45 — — 343 1 to 339 2 0.1-89  0-180 — 344 1 to 339 2 0.1-89   5-75 — 345 1 to 339 2 0.1-89  10-45 —346 1 to 339 2  5-75  0-180 — 347 1 to 339 2  5-75  5-75 — 348 1 to 3392  5-75 10-45 — 349 1 to 339 2 10-45  0-180 — 350 1 to 339 2 10-45  5-75— 351 1 to 339 2 10-45 10-45 — 352 1 to 339 3 0.1-89   0-180  0-180 3531 to 339 3 0.1-89   0-180  5-75 354 1 to 339 3 0.1-89   0-180 10-45 3551 to 339 3  5-75  0-180  0-180 356 1 to 339 3  5-75  0-180  5-75 357 1to 339 3  5-75  0-180 10-45 358 1 to 339 3 10-45  0-180  0-180 359 1 to339 3 10-45  0-180  5-75 360 1 to 339 3 10-45  0-180 10-45 361 1 to 3393 0.1-89   5-75  0-180 362 1 to 339 3 0.1-89   5-75  5-75 363 1 to 339 30.1-89   5-75 10-45 364 1 to 339 3  5-75  5-75  0-180 365 1 to 339 3 5-75  5-75  5-75 366 1 to 339 3  5-75  5-75 10-45 367 1 to 339 3 10-45 5-75  0-180 368 1 to 339 3 10-45  5-75  5-75 369 1 to 339 3 10-45  5-7510-45 370 1 to 339 3 0.1-89  10-45  0-180 371 1 to 339 3 0.1-89  10-45 5-75 372 1 to 339 3 0.1-89  10-45 10-45 373 1 to 339 3  5-75 10-45 0-180 374 1 to 339 3  5-75 10-45  5-75 375 1 to 339 3  5-75 10-45 10-45376 1 to 339 3 10-45 10-45  0-180 377 1 to 339 3 10-45 10-45  5-75 378 1to 339 3 10-45 10-45 10-45

Optionally, a second heating step with an IR heating system with one ortwo rollers is done according to table VI.

TABLE VI Spraying embodiment followed Embodi- directly by Number of mentthe heating compression no. step rollers Angle α′₁ (°) Angle α′₂ (°) 379340 to 378 1 0.1-89  — 380 340 to 378 1  5-75 — 381 340 to 378 1 10-45 —382 340 to 378 2 0.1-89   0-180 383 340 to 378 2 0.1-89   5-75 384 340to 378 2 0.1-89  10-45 385 340 to 378 2  5-75  0-180 386 340 to 378 2 5-75  5-75 387 340 to 378 2  5-75 10-45 388 340 to 378 2 10-45  0-180389 340 to 378 2 10-45  5-75 390 340 to 378 2 10-45 10-45

EXAMPLES

The following examples provide a non-limiting illustration of the scopeof the invention.

Example 1 Comparison

A 12K carbon fiber roving was impregnated with PA 11/6T/10T, asdescribed in WO 2015/121583.

D50=100 μM.

Results:

The results are shown in FIG. 9 and show a lack of homogeneity inseveral locations of the impregnated roving diagrammed by the whitearrows.

Example 2 General Procedure Comprising a Step for the Pre-Impregnationof a Fibrous Material (Carbon Fiber) With a PEKK Powder in a TankComprising a Fluidized Bed Provided With a Single Roller and a Step forInfrared Heating

The following procedure was carried out:

Pre-Impregnation Step

-   -   A cylindrical compression roller R₁ in the tank (L=500 mm, 1=500        mm, H=600 mm), diameter 25 mm.    -   Residence time of 0.3 s in the powder    -   Angle α₁ of 25°    -   Expansion about 100% (or a width multiplied by 2) for a carbon        fiber roving of Toray ¼″ carbon, 12K T700S 31E    -   D50=51 μm, (D10=21 μm, D90=97 μm) for the PEKK powder.    -   edge of the tank equipped with a stationary roller.

The fibrous material (¼″ carbon fiber roving) was pre-impregnated with apolymer (PEKK with particle size defined hereinabove) according to thisprocedure.

Heating Step:

The heating system used is that described in FIG. 1, but with eightstationary cylindrical rollers R′₁ to R′₈ with diameter 8 mm.

The speed of advance of the roving is 10 m/min.

The infrared used has a power of 25 kW, the height between the infraredand the upper roller is 4 cm and the height between the infrared and thelower rollers is 9 cm.

The angles α′₁ to α′_(s) are identical and 25°.

The height h is 20 mm.

The length I is 1000 mm. These eight rollers are each separated by 43mm.

Calendaring using two calendars mounted in series equipped with an IR of1 kW each after the heating step.

FIG. 18 shows the impregnated fibrous material obtained with PEKK.

This demonstrates the effectiveness of the impregnation method by a drypowder in fluidized bed with a compression roller and controls theresidence time in the powder combined with a heating step.

Example 3 General Procedure Comprising a Step for the Preimpregnation ofa Fibrous Material (Carbon Fiber) by a Polyamide Powder (MPMDT/10T) in aTank Comprising a Fluidized Bed and Provided With a Single Roller and aStep For Infrared Heating, Four Rollers Preceding the Tank (UpstreamSupporters)

The four rollers preceding the tank are cylindrical and stationary witha diameter of 8 cm. The rollers are 54 cm apart (distance between thefirst and last roller).

Pre-Impregnation and Heating Step:

The pre-impregnation step and the heating step are identical to example2, but the polymer used is as follows:

D50=115 μm, (D10=49 μm, D90=207 μm) for the MPMDT/10T powder.

Calendaring using two calendars mounted in series equipped with an IR of1 kW each after the heating step.

The results obtained are similar to those of example 2.

Example 4 Determination of the Porosity Level by Image Analysis:

The porosity was determined by image analysis on a ¼″ carbon fiberroving impregnated by MPMDT/10T in fluidized bed with upstreamsupporters followed by a heating step as defined hereinabove.

It is less than 5%.

Example 5 Determination of the Porosity Level the Relative DeviationBetween Theoretical Density and Experimental Density (general Method):

a) The required data are:

-   -   The density of the thermoplastic matrix    -   The density of the fibers    -   The grammage of the reinforcement:        -   linear mass (g/m) for example for a ¼ inch tape (coming from            a single roving)        -   surface density (g/m²) for example for a wider tape or a            fabric

b) Measurements to be done:

The number of samples must be at least 30 in order for the result to berepresentative of the studied material:

The measurements to be done are:

-   -   The size of the samples taken:        -   Length (if linear mass is known).        -   Length and width (if surface density is known).    -   The experimental density of the samples taken:        -   Mass measurements in the air and in water.    -   The measurement of the fiber level is determined according to        ISO 1172:1999 or by thermogravimetric analysis (TGA) as        determined for example in the document B. Benzler,        Applikationslabor, Mettler Toledo, Giesen, UserCom 1/2001.

The measurement of the carbon fiber level can be determined according toISO 14127:2008.

Determination of the theoretical mass fiber level:

a) Determination of the theoretical mass fiber level:

${\%\mspace{14mu}{Mf}_{th}} = \frac{m_{l} \cdot L}{Me_{air}}$

With

m_(l) the linear mass of the tape,

L the length of the sample, and

Me_(air) the mass of the sample measured in the air.

The variation of the mass fiber level is presumed to be directly relatedto a variation of the matrix level without taking account of thevariation of the quantity of fibers in the reinforcement.

b) Determination of the theoretical density:

$d_{th} = \frac{1}{\frac{1 - {\%\mspace{14mu}{Mf}_{th}}}{d_{m}} + \frac{\%\mspace{14mu}{Mf}_{th}}{d_{f}}}$

With d_(m) and d_(f) the respective densities of the matrix and thefibers.

The theoretical density thus calculated is the accessible density ifthere is no porosity in the samples.

c) Evaluation of the porosity:

The porosity is then the relative deviation between theoretical densityand experimental density.

Embodiments

1. A method of manufacturing an impregnated fibrous material comprisinga fibrous material made of continuous fibers and at least onethermoplastic polymer matrix, characterized in that said impregnatedfibrous matrix is produced as a single unidirectional ribbon or aplurality of unidirectional parallel ribbons and characterized in thatsaid method comprises a step of pre-impregnating said fibrous materialwhile it is in the form of a roving or several parallel rovings with thethermoplastic material and at least one step of heating thethermoplastic matrix for melting, or maintaining in the molten state,the thermoplastic polymer after pre-impregnation,

the at least one heating step being carried out by means of at least oneheat-conducting supporting part (E) and at least one heating system,with the exception of a heated calendar,

the roving or rovings being in contact with the part or all of thesurface of the at least one supporting part (E) and partially or whollypassing over the surface of the at least one supporting part (E) at thelevel of the heating system, excluding any electrostatic method withdeliberate charge,

and the porosity level in said pre-impregnated fibrous material beingless than 10%, in particular less than 5%, particularly less than 2%.

2. The method according to embodiment 1, characterized in that saidpre-impregnated fibrous material is not flexible.

3. The method according to embodiment 1 or 2, characterized in that thepre-impregnation step is done with a system chosen from among afluidized bed, a spray gun and the molten route, in particular at a highspeed, particularly the pre-impregnation is done in a fluidized bed.

4. The method according to embodiment 3, characterized in that one ormore supporter(s) (E″) is (are) present upstream from said system.

5. The method according to one of embodiments 1 to 4, characterized inthat a pre-impregnation step and a heating step are carried out, saidheating step immediately following the pre-impregnation step.

6. The method according to one of embodiments 1 to 5, characterized inthat said at least one heating system is chosen from among an infraredbulb, a UV bulb and convection heating.

7. The method according to one of embodiments 1 to 6, characterized inthat said at least one supporting part (E) is a compression roller R′iwith a convex, concave or cylindrical shape, preferably cylindrical.

8. The method according to embodiment 7, characterized in that said atleast one supporting part (E) is made up of 1 to 15 cylindricalcompression rollers (R′₁ to R′₁₅), preferably 3 to 15 compressionrollers (R′₃ to R′₁₅), in particular 6 to 10 compression rollers (R′₆ toR′₁₀).

9. The method according to one of embodiments 7 or 8, characterized inthat said roving(s) form(s) an angle α′₁ of 0.1 to 89°, in particular of5 to 75°, in particular of 10 to 45° with a first compression roller R′₁and the horizontal tangent to said roller R′₁, said roving(s) expandingin contact with said compression roller.

10. The method according to embodiment 7, characterized in that a secondroller R′₂ is present after said first compression roller R′₁, saidroving(s) forming an angle α′₂ of 0 to 180°, in particular of 5 to 75°,in particular of 10 to 45° with said second compression roller R′₂ andthe horizontal tangent to said roller R′₂, said roving(s) expanding incontact with said compression roller.

11. The method according to embodiment 8, characterized in that at leastone third roller R′₃ is present after said second roller R′₂, saidroving(s) forming an angle α′₃ of 0 to 180°, in particular of 5 to 75°,in particular of 10 to 45° with said third compression roller R′₃ andthe horizontal tangent to said compression roller R′₃, said roving(s)expanding in contact with said third compression roller R′₃.

12. The method according to embodiment 8, characterized in that six toten rollers are present and at the same level.

13. The method according to one of embodiments 1 to 12, characterized inthat the spreading percentage at the outlet of the last compressionroller R′_(i) is about 0 to 300%, in particular 0 to 50%, relative tothat of said roving(s) at the inlet of the first compression rollerR′₁..

14. The method according to one of embodiments 1 to 13, characterized inthat said thermoplastic polymer is a nonreactive thermoplastic polymer.

15. The method according to one of embodiments 1 to 13, characterized inthat said thermoplastic polymer is a reactive pre-polymer capable ofreacting with itself or with another pre-polymer, based on the chainends of said pre-polymer, or with another chain extender, said reactivepolymer optionally being polymerized during the heating step.

16. The method according to one of embodiments 1 to 15, characterized inthat said at least one thermoplastic polymer is selected from: polyarylether ketones (PAEK), in particular polyether ether ketone (PEEK);polyaryl ether ketone ketone (PAEKK), in particular polyether ketoneketone (PEKK); aromatic polyether imides (PEI); polyaryl sulfones, inparticular polyphenylene sulfones (PPSU); polyarylsulfides, inparticular polyphenylene sulfides (PPS); polyamides (PA), in particularsemi-aromatic polyamides (polyphthalamides) optionally modified by ureaunits; PEBAs, polyacrylates in particular polymethyl methacrylate(PMMA); polyolefins in particular polypropylene, polylactic acid (PLA),polyvinyl alcohol (PVA), and fluorinated polymers in particularpolyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) orpolychlorotrifluoroethylene (PCTFE); and mixtures thereof, in particulara mixture of PEKK and PEI, preferably from 90-10% by weight to 60-40% byweight, in particular from 90-10% by weight to 70-30% by weight.

17. The method according to one of embodiments 1 to 16, characterized inthat said at least one thermoplastic polymer is a polymer whose glasstransition temperature is such that Tg≥80° C., in particular 100° C.,particularly 120° C., in particular 140° C., or a semi-crystallinepolymer whose melting temperature Tm 150° C.

18. The method according to one of embodiments 1 to 17, characterized inthat said at least one thermoplastic polymer is selected frompolyamides, in particular aliphatic polyamides, cycloaliphaticpolyamides and semi-aromatic polyamides (polyphthalamides), PVDF, PEEK,PEKK, PEI and a PEKK and PEI mixture.

19. The method according to one of embodiments 1 to 18, characterized inthat the fiber level in said pre-impregnated fibrous material is between45 to 65% by volume, preferably from 50 to 60% by volume, in particularfrom 54 to 60%.

20. The method according to one of embodiments 1 to 19, characterized inthat the porosity level in said pre-impregnated fibrous material is lessthan 10%, in particular less than 5%, particularly less than 2%.

21. The method according to one of embodiments 1 to 20, characterized inthat it also comprises a step for shaping said roving or said parallelrovings of said impregnated fibrous material, by calendaring using atleast one heating calendar in the form of a single unidirectional ribbonor a plurality of parallel unidirectional ribbons with, in the lattercase, said heating calendar including a plurality of calendaring grooves(73), preferably up to 200 calendaring grooves, in accordance with thenumber of said ribbons and with a pressure and/or separation between therollers of said calendar regulated by a governing system.

22. The method according to embodiment 21, characterized in that thecalendaring step is done using a plurality of heating calendars, mountedin parallel and/or in series relative to the passage direction of thefiber rovings.

23. The method according to one of embodiments 21 or 22, characterizedin that said heating calendar(s) comprise(s) an integrated induction ormicrowave heating system, preferably microwave, coupled with thepresence of carbon fillers in said thermoplastic polymer or mixture ofthermoplastic polymers.

24. The method according to one of embodiments 1 to 223, characterizedin that a belt press is present between the heating system and thecalendar.

25. The method according to one of embodiments 1 to 23, characterized inthat a heating nozzle is present between the heating system and thecalendar.

26. The method according to one of embodiments 1 to 23, characterized inthat a belt press is present between the heating system and the calendarand a heating nozzle is present between the belt press and the calendar.

27. The method according to one of embodiments 1 to 26, characterized inthat said pre-impregnation and impregnation steps are completed by astep for covering said single roving or said plurality of parallelrovings after impregnation by the powder, said covering step being donebefore said calendaring step, with a molten thermoplastic polymer, whichmay be identical to or different from said pre-impregnation polymer,said molten polymer preferably being of the same nature as saidpre-impregnation polymer, preferably with said covering being done bycrosshead-die extrusion relative to said single roving or said pluralityof parallel rovings.

28. The method according to one of embodiments 1 to 27, characterized inthat said thermoplastic polymer further comprises carbonaceous fillers,in particular carbon black or carbon nanofillers, preferably selectedfrom carbonaceous nanofillers, in particular graphenes and/or carbonnanotubes and/or carbon nanofibrils or mixtures thereof.

29. The method according to one of embodiments 1 to 28, characterized inthat said fibrous material comprises continuous fibers selected fromcarbon, glass, silicon carbide, basalt, silica, natural fibersespecially flax or hemp, lignin, bamboo, sisal, silk, or cellulose, inparticular viscose, or amorphous thermoplastic fibers with a glasstransition temperature

Tg higher than the Tg of said polymer or said polymer mixture when thelatter is amorphous or higher than the Tm of said polymer or saidpolymer mixture when the latter is semi-crystalline, or thesemi-crystalline thermoplastic fibers with a melting temperature Tmhigher than the Tg of said polymer or said polymer mixture when thelatter is amorphous or higher than the Tm of said polymer or saidpolymer mixture when the latter is semi-crystalline, or a mixture of twoor more of said fibers, preferably a mixture of carbon fibers, glass orsilicon carbide, in particular carbon fibers.

30. A unidirectional ribbon of pre-impregnated fibrous material, inparticular ribbon wound on a spool, characterized in that it is obtainedby a method as defined according to one of embodiments 1 to 29.

31. The ribbon according to embodiment 30, characterized in that it hasa width (I) and thickness (ep) suitable for robot application in themanufacture of three-dimensional workpieces, without the need forslitting, the width (I) being of at least 5 mm and up to 400 mm,preferably between 5 and 50 mm, and even more preferably between 5 and15 mm.

32. The ribbon according to one of embodiments 30 or 31, characterizedin that the thermoplastic polymer is an aliphatic polyamide selectedfrom PA 6, PA 11, PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA 1012,PA 11/1010 or PA 12/1010 or a semi-aromatic polyamide such as PA MXD6and PA MXD10 or chosen from PA 6/6T, PA 61/6T, PA 66/6T, PA 11/10T, PA11/6T/10T, PA MXDT/10T, PA MPMDT/10T, PA BACT/6T, PA BACT/10T and PABACT/10T/6T, PVDF, PEEK, PEKK and PEI or a mixture thereof.

33. Use of a method as defined by one of embodiments 1 to 29, for themanufacture of calibrated ribbons suitable for the manufacture ofthree-dimensional composite parts, by the automatic laying of the saidribbons by means of a robot.

34. Use of a ribbon of pre-impregnated fibrous material, as definedaccording to one of embodiments 30 to 32, in the manufacture ofthree-dimensional composite parts.

35. Use according to embodiment 33 or 34, characterized in that saidmanufacture of said composite parts concerns the fields oftransportation, in particular automotive, oil and gas, in particularoffshore, gas storage, aeronautics, naval, railways; renewable energiesselected from wind energy, hydro turbines, energy storage devices, solarpanels; thermal protection panels; sports and leisure, health andmedical and electronics.

36. Three-dimensional composite part, characterized in that it resultsfrom the use of at least one unidirectional ribbon of pre-impregnatedfibrous material as defined according to one of embodiments 30 to 32.

1. An impregnated fibrous material comprising a fibrous material ofcontinuous fibers and at least one thermoplastic polymer matrix, whereinat least one thermoplastic polymer is a non-reactive amorphous polymerwhose glass transition temperature is such that Tp≥80° C., or anon-reactive semi-crystalline polymer whose melting temperature isTf≥150° C., where Tg and Tf are determined by differential scanningcalorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013respectively, a fiber content by volume is constant in at least 70% ofthe volume of the impregnated fibrous material, the fiber content insaid impregnated fibrous material being between 45 and 65% by volume onboth sides of said fibrous material, a porosity rate in said impregnatedfibrous material being less than 10%, said impregnated fibrous materialbeing free of non-reactive liquid crystal polymers (LCP), wherein anumber average molecular weight (Mn) changes by less than 50% during itsimplementation, wherein impregnation is carried out with at least oneexpansion.
 2. The impregnated fibrous material according to claim 1,wherein at least one thermoplastic polymer is selected from: polyarylether ketones (PAEK); polyaryl ether ketone ketone (PAEKK); aromaticpolyether imides (PEI); polyaryl sulfones; polyarylsulfides; polyamides(PA); polyether block amides (PEBAs); polyolefins; and mixtures thereof.3. The impregnated fibrous material according to claim 1, wherein the atleast one thermoplastic polymer is selected from polyamides, polyetherether ketones (PEKK), aromatic polyether imides (PEI) and a mixture ofPEKK and PEI.
 4. The impregnated fibrous material according to claim 3,wherein said polyamides are selected from aliphatic polyamides,cycloaliphatic polyamides and semi-aromatic polyamides(polyphthalamides).
 5. The impregnated fibrous material according toclaim 4, wherein said aliphatic polyamide is selected from polyamide 6(PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66(PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612(PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide11/1010, polyamide 12/1010, or a mixture thereof or a copolyamidethereof, and block copolymers, and said semi-aromatic polyamides, is asemi-aromatic polyamide, optionally modified with urea units selectedfrom an MXD6 and an MXD10 or a semi-aromatic polyamide of formula X/YAr,selected from a semi-aromatic polyamide of formula A/X.T in which A isselected from a unit obtained from an amino acid, a unit obtained from alactam and a unit corresponding to the formula (Ca diamine).(Cb diacid),with a representing the number of carbon atoms of the diamine and brepresenting the number of carbon atoms of the diacid, a and b eachbeing between 4 and 36, the unit (Ca diamine) being selected fromaliphatic diamines, linear or branched, cycloaliphatic diamines andalkylaromatic diamines and the unit (Cb diacid) being chosen fromaliphatic, linear or branched diacids, cycloaliphatic diacids andaromatic diacids; X.T denotes a unit obtained from the polycondensationof a Cx diamine and terephthalic acid, with x representing the number ofcarbon atoms of the Cx diamine, x being between 6 and 36, Tcorresponding to terephthalic acid, MXD corresponding to m-xylylenediamine.
 6. The impregnated fibrous material according to claim 1,wherein said fibrous material comprises continuous fibers selected fromcarbon, glass, silicon carbide, basalt, silica, flax or hemp, lignin,bamboo, sisal, silk, or cellulose, or amorphous thermoplastic fiberswith a glass transition temperature Tg higher than the Tg of saidthermoplastic polymer matrix when the latter is amorphous or higher thanthe Tf of said thermoplastic polymer matrix when the latter issemi-crystalline, or the semi-crystalline thermoplastic fibers with amelting temperature Tf higher than the Tg of said thermoplastic polymermatrix when the latter is amorphous or higher than the Tf of saidthermoplastic polymer matrix when the latter is semi-crystalline, or amixture of two or more of said fibers.
 7. The impregnated fibrousmaterial according to claim 1, wherein said thermoplastic polymerfurther comprises carbonaceous fillers.
 8. A method of using theimpregnated fibrous material, as defined in claim 1, for the preparationof calibrated ribbons suitable for the manufacture of three-dimensionalcomposite parts by automatic application of said ribbons by means of arobot.
 9. A ribbon comprising at least one impregnated fibrous materialas defined in claim
 1. 10. The ribbon according to claim 9, wherein itis made of a single unidirectional ribbon or a plurality of parallelunidirectional ribbons.
 11. The ribbon according to claim 9, wherein ithas a width (I) and a thickness (ep) suitable for robot application inthe manufacture of three-dimensional workpieces, without the need forslitting, the width (I) being of at least 5 mm and up to 400 mm.
 12. Theribbon according to claim 10, wherein the at least one thermoplasticpolymer is a polyamide selected from an aliphatic polyamide PA 6, PA 11,PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA 1012, PA 11/1010 or PA12/1010 or a semi-aromatic polyamide selected from a PA MXD6 and a PAMXD10 or chosen from PA 6/6T, PA 61/6T, PA 66/6T, PA 11/10T, PA11/6T/10T, PA MXDT/10T, PA MPMDT/10T, PA BACT/6T, PA BACT/10T and PABACT/10T/6T, a poly(vinylidene fluoride) (PVDF), a polyether etherketone (PEEK), polyether ketone ketone (PEKK), and an aromatic polyetherimide (PEI) or a mixture thereof.
 13. The ribbon according to claim 12,wherein the thermoplastic polymer is a polyamide selected from analiphatic polyamide selected from PA 6, PA 11, PA 12, PA 11/1010 or PA12/1010 or a semi-aromatic polyamide selected from PA 6/6T, PA 61/6T, PA66/6T, PA 11/10T, PA 11/6T/10T, PA MXDT/10T, PA MPMDT/10T and PABACT/10T, T corresponding to terephthalic acid, MXD corresponding tom-xylylene diamine, MPMD corresponding to methylpentamethylene diamineand BAC corresponding to bis(aminomethyl)cyclohexane.
 14. A method ofusing the ribbon, as defined according to claim 9, in the manufacture ofthree-dimensional composite parts.
 15. The method according to claim 14,wherein said manufacture of said composite parts relates to the fieldsof transportation, oil and gas, gas storage, aeronautics, nautical,railways; renewable energies selected from wind energy, hydro turbines,energy storage devices, solar panels; thermal protection panels; sportsand leisure, health and medical and electronics.
 16. A three-dimensionalcomposite part, wherein it results from the use of at least oneunidirectional ribbon of impregnated fibrous material as definedaccording to claim 9.